Veterans and Violence Part 2: Forensic Psychological and Neuropsychological Evaluations of Veterans with PTSD and TBI

Legal applications and implications

Part I of this article was run in the October 2020 issue. Part II of this article focuses on the application of forensic psychological and neuropsychological evaluation to veterans with PTSD and TBI. 

Forensic neuropsychology is defined as the application of neuropsychological assessment and the examination of brain behavior relationships to criminal or civil litigants. Forensic neuropsychologist experts provide reliable valid assessment and data about the relationship between neurocognitive dysfunction and neuropathology and the behavioral and/or cognitive issues related to legal questions in court proceedings.  

Neuropsychological assessment is very sensitive to brain function and dysfunction and can be helpful in determining forensic/legal issues. Similarly, the forensic psychologist examines psychological and psychiatric functioning of an individual and applies this clinical assessment to forensic and legal issues. The forensic neuropsychologist who also practices as a forensic psychologist will often integrate a nexus between psychological and neuropsychological brain function/dysfunction, psychiatric diagnosis, and specific symptoms to the violent act.

In addition to the forensic neuropsychological assessment of veterans to examine brain function and dysfunction, the forensic neuropsychologist will often assist in integrating their brain behavior data with neuroimaging. Structural and function neuroimaging is useful in further assessing the specific locations of the brain that may be low in volume and density. In these cases, the PTSD and TBI conditions and their effects on an individual’s neuropathology are often cited in the limbic system and amygdala and hippocampus as well as the prefrontal cortex. Ideally, the neuropsychological assessment will be correlated with the neuroimaging findings (executive functioning deficits in the prefrontal cortex and attention, memory, and behavioral dysregulation, attention, and paranoia in the limbic system). 

The forensic neuropsychological assessment in veterans in criminal cases may include the following legal referral questions:

  1. Competency to stand trial
  2. Not guilty by reason of insanity
  3. Diminished capacity
  4. Voluntary intoxication and diminished capacity
  5. Self-defense
  6. Mitigation for plea negotiation and/or sentencing
  7. Issues relating to future dangerousness, lack thereof, and violence and sexual violence risk assessment and risk management

I will address some of these forensic legal issues concerning veterans, PTSD, and TBI below. 

The forensic neuropsychological assessment of veterans may ultimately focus on the prevalence and cumulative impact of co-occurring neuropsychological and psychiatric conditions including PTSD, TBI, depression, and substance intoxication/addiction on the veteran’s mental state at the time of the violent act(s). The forensic neuropsychologist may also offer valuable insight into the complex emotional, behavioral, and neuropsychological effects and function of brain injury and PTSD in relation to a veteran’s propensity for violence.

Issues related to behavioral dyscontrol, impulsivity, dissociation, paranoia, suicidality, and intoxication are germane to both TBI, PTSD, and other comorbid conditions that are prevalent with intense combat related military service.

Three major areas of forensic assessment with TBI and PTSD in military related criminal justice cases include diminished capacity, self-defense, insanity, and mitigation. Essentially, all these forensic referral questions address the defendant’s mental state at the time of the offense. 

Diminished Capacity

In military cases, the effects of TBI and or PTSD on one’s emotional, behavioral, and cognitive functioning can be applied to the mens rea elements of a violent crime.

Diminished capacity in criminal cases is typically recognized as whether the defendant, due to mental disease and/or defect, had the capacity to form the requisite mental state constituting a crime. This proposition is supported by opinions issued from the Courts of Appeal.

In Jackson v. State,1 diminished capacity was presented as a failure-of-proof claim. The prosecution failed to prove that the defendant had the required state of mind at the time of the offense. To counter the prosecution’s evidence of the defendant’s culpable state of mind, the defense may present evidence that the defendant has mental or physical impairments or abnormalities and that some of his abilities are lessened in comparison to someone without such problems.

Evidence of mental disease or defect that directly rebuts a particular mens rea necessary for the charged offense can be presented by either lay or expert witnesses. In Lizcano v. State,2 the Court recognized diminished capacity with mental health testimony only if it negates any mens rea element. The defense must make a showing of a connection between the defendant’s psychological and neuropsychological functioning and how impairments could negate a mens rea element. 

In Lizcano, the defendant was charged with the offense of capital murder in the shooting death of a police officer. During trial, the trial court excluded evidence related to the defendant’s mental health. On appeal, the defendant argued that the excluded mental health testimony was relevant as to whether, because of mental disease or delusion, the defendant believed he was not shooting at a uniformed police officer. He  further argued that evidence of how paranoid delusions may distort a person’s auditory and visual perceptions is admissible as it relates to the defendant’s intent to shoot a police officer. The Court found there was no suggestion in the trial record that the excluded testimony had anything to do with delusions. Instead, the court concluded the excluded testimony suggested general limitations in cognitive ability and intoxication at the time of the offense as well as general deficits in adaptive functioning. The excluded testimony had relevance only as to whether the defendant’s mental functioning was below normal to some degree. There was no evidence showing a connection between the defendant’s generally low level of mental functioning and his knowledge during the commission of the offense that the victim was a police officer. 

In State v. Ruffin,3 Ruffin was charged with aggravated assault after shooting at police officers. At the time of the shooting, he believed the officers were trespassers and Muslims rather than police officers. At trial, the psychologist for the defense testified that Ruffin suffered from delusions and opined that he was suffering from psychotic symptoms such as auditory and visual hallucinations at the time of the offense. The trial court found the testimony of the psychologist was relevant and admissible to rebut the mens rea element of the offense. In essence, the Court emphasized that any expert testimony regarding diminished capacity and mens rea issues during the guilt and innocence phase of the trial must not only focus on mental illness, psychiatric symptoms, level of functioning, and possible brain damage and dysfunction, but there must also be a showing of how those symptoms and impairments specifically negate the defendant’s mens rea. 

Similarly, in Nikmanesh v. State,4 the Court of Appeals found the trial court did not err in excluding psychiatric evidence where expert testimony concerning the defendant’s behavior, depressive disorder, and obsessive-compulsive disorder could only offer an explanation or motive for his actions but could not negate intent for an offense of murder. 

Ultimately, diminished capacity mental health testimony not directly rebutting intent will not be admitted in Texas courts.5 An expert witness in a case where PTSD and TBI are present must not only present testimony on symptoms of psychiatric disorder and neurocognitive impairments of brain disorder but apply this information to the defendant’s incapability of forming intent to commit the act or incapability of acting with knowledge of their conduct and its consequences.6 Presenting expert testimony only on symptoms, conditions, diagnoses, and impairments without applying this data to the defendant’s mental state at the time of the offense(s), and specifically to their intent, will not be permitted.

Information as to mitigating mental state evidence of PTSD and/or TBI in military and civilian cases can assist the trier of fact in appreciating the defendant’s mental state and history. In many violent murder and assault cases defendants have a profound history of abuse, neglect, early trauma, and complex trauma suffered through childhood, histories of psychiatric disorders, and dual-diagnostic disorders with chemical dependency and addiction. The military servicemen and women who commit violent crimes often have these same traumatic and dysfunctional histories, but they also may have military trauma histories related to PTSD and brain injury. 

Additionally, in cases with genuine military-based trauma often suffered and acquired through combat, the trier of fact may recognize mitigating factors regarding service to country. Reporting this trauma through presentation of forensic expert reports is also bolstered by providing the trier of fact with VA and military records which may provide even more legitimacy of the trauma. 

Case Studies

In a case of diminished capacity, this author examined a 22-year-old non-military defendant charged with two counts of aggravated assault of a public servant with a deadly weapon and evading arrest/detention in a motor vehicle. The defendant’s father had a traumatic brain injury causing him severe anger problems, and he physically abused the defendant. The defendant also had prior acts of violence towards family members. The defendant suffered from a childhood history of ADHD and early behavioral problems, and there were early concerns about autism spectrum disorder. Once he reached adulthood, he was more floridly psychotic with a schizophrenia diagnosis and experienced auditory hallucinations and paranoid delusions. 

The evening of the offense, the defendant was paranoid and psychotic and was audio and video recording family members due to his paranoia. Arguing ensued between the defendant and his father and grandfather, and the defendant yelled out that he had to leave because of the demons. He ran out of the house, got into a car, and started driving in an acute psychotic state. The family had called 911, and the police responded immediately. The defendant was driving erratically, and the officer perceived the defendant driving toward him and felt threatened, attempted to stop the car by moving to the other lane, and utlimately steered his vehicle toward the defendant’s car, ramming it to its halt. The officer got out of the car and grabbed the defendant’s passenger door handle when the defendant failed to follow the officer’s commands. The officer fired his weapon twice as the defendant’s vehicle approached him.

During a 7027 hearing at the guilt/innocence phase of the trial, the author’s testimony addressed the defendant’s mental state at the time of the alleged offense. The defendant was significantly compromised by his mental conditions related to schizoaffective disorder bipolar type, active paranoid delusions, auditory hallucinations, PTSD, and ADHD. Also present was the hyperarousal and fight/flight phenomenon. These disorders would impair an individual’s cognitive functioning, ultimate problem solving, and decision-making skills in a time of heightened stress, extreme paranoia, and perceived threat. The testimony was admitted by the court to inform the jury as to how these psychiatric symptoms collectively negated the defendant’s mental state to commit aggravated assault against a police officer. 

In another Texas case, this author examined a 61-year-old Vietnam veteran charged with online solicitation of a minor under age 14. He served one tour in Vietnam where he witnessed and experienced significant war-related trauma, and as a result, there was evidence of PTSD and severe alcoholism, depression, and anxiety. The was also evidence of childhood neurodevelopmental disorder. He had treatment and disability through the VA for mental health conditions. He suffered one traumatic brain injury after the war from an assault and another when he was hit by a car. The trial court judge held a 702 hearing and allowed mental health testimony regarding the defendant’s mental state and intent as to following through with solicitation type text messages to a minor girl. Essentially, the author examined and testified to significant brain dysfunction, neurocognitive and neurodevelopmental disorders, coupled with his mental illness and how these disorders in collection compromised his mental state and negated his intent regarding solicitation, as well as testimony regarding his intent in carrying out any type of sexual acts with the victim. 

Sudden Passion, Manslaughter, and Criminal Homicide

Another area of criminal law where PTSD and TBI evidence may apply is in the defense of criminal homicide (Texas Penal Code §19.01).8 “Criminal Homicide” covers the offenses of Murder (§19.02), Capital Murder (§19.03), Manslaughter (§19.04), and Criminally Negligent Homicide (§19.05). 

Pursuant to §19.02, a person commits the offense of murder if he: 

  1. Intentionally or knowingly causes the death of an individual;
  2. Intends to cause serious bodily injury and commits an act clearly dangerous to human life that causes death of an individual; or
  3. Commits or attempts to commit a felony, other than manslaughter, and in the course of an in furtherance of the commission or attempt, or in the immediate flight from the commission or attempt, he commits or attempts to commit an act clearly dangerous to human life that causes the death of an individual. 

Murder is a first-degree felony with a range of punishment of 5-99 years or Life in the Texas Department of Corrections (TDC). Should the defense prove the defendant acted with “sudden passion” the jury may sentence the defendant as if it were a second-degree felony, which has a range of punishment of 2-20 years in TDC. “Sudden passion” means passion directly caused by and arising out of provocation by the individual killed or another acting with the person killed, which passion arises at the time of the offense and is not solely the result of former provocation. 

Critical to murder cases is an instruction for manslaughter. Under §19.04, a person commits the offense of manslaughter if he recklessly causes the death of an individual. Mental health and brain behavior-based PTSD and TBI evidence may apply to negate a defendant’s intentionally or knowingly causing the death of an individual. The conditions, symptoms, and impairments of PTSD and TBI apply well with reckless behavior. Per §6.03(c), a person is reckless when they are aware of the risks surrounding their conduct and of the results that could occur but consciously disregard that awareness. Importantly, the risk must be of such a nature and degree that its disregard constitutes a gross deviation from the standard of care that an ordinary person would exercise under all the circumstances as viewed from the actor’s standpoint. The crime does not require an element of premeditation, intent, or knowledge, only that a person is reckless. 

PTSD and TBI can affect several critical domains of functioning at or around the time of violent acts leaving an individual vulnerable to misperceiving provocation, overreacting, and becoming impulsive and reckless in their reactions and behavior. Some of these domains include cognition, emotion, behavior, and physiological arousal. PTSD and TBI can also dramatically affect the way an individual perceives, processes, and responds to people and situations. These conditions place individuals at risk for paranoia, impulsivity, deficient problem solving, and deficits in cool reflection with poor appreciation of consequences. 

Critical neural circuitry areas of the brain and in particular, the areas regarding impulse control, learning from experience, problem solving, and decision making are especially susceptible to PTSD and TBI. An individual with PTSD and/or TBI, but especially both together, can misperceive threat and provocation due to a number of issues including paranoia, deficient emotional processing, and behavioral regulation.


Another area of mental state evidence and the law in which psychological and neuropsychological evidence can be considered is self-defense.9 Under Texas Penal Code 9.31, self-defense can be invoked when “a person is justified in using force against another when he believes the force is immediately necessary to protect himself against the other’s use or attempted use of unlawful force.”  Self-defense is an affirmative defense, and the defendant bears the burden of production. He must present some evidence of a specific apparent danger and that the use of force or deadly force was reasonable and necessary to avoid the danger.10 The reasonableness of the actor’s belief that force or deadly force is immediately necessary is judged from the standpoint of an ordinary person under the same circumstances as the actor. A person “has a right to defend from apparent danger to the same extent as he would had the danger been real; provided that he acted upon a reasonable apprehension of danger as it appeared to him at the time.”11 The defense attorney may argue that their client’s PTSD, complex trauma, or TBI related brain damage/dysfunction are circumstances that must be considered by the trier of fact in a self-defense case.

A veteran suffering from PTSD/TBI is at particular risk to have a compromised fight/flight system. Evidence of complex trauma and PTSD place a veteran at risk to misperceive threat, to be constantly on edge, hypervigilant, and in an overstimulated and impulsive state. Those with TBI often have faulty brakes to balance the impulsive threat response system. 

Case Study

In a self-defense trial, this author examined a 74-year-old Vietnam veteran charged with murder. The defendant was accused of murdering his neighbor who was also a Vietnam veteran, and with whom for several years, he shared a chronic tumultuous history. The defendant perceived death threats from the neighbor, and on the day of the shooting, he said the victim assaulted him on his own property by punching and striking him multiple times. He also perceived the victim pulling out a weapon (an aluminum cane) and threatening the defendant and yelling that he wished the defendant would die. While the defendant was trying to retreat, the victim continued punching him, which led to a mutual fight. There was a verbal and physical argument over the weapon. While the victim was beating him with the cane, the defendant pulled out a gun and shot and killed the victim. During my examination the defendant said, “When I pulled the trigger I was in fear for my life.” 

The defendant had a history of trauma prior to his war experiences which led to his PTSD symptoms. His biological father had a history of alcohol use and abuse and died of cirrhosis of the liver when the defendant was age 6. The defendant then lived in an extremely dysfunctional household with his mother, who had evidence of mental illness, and his grandparents. The defendant only completed ninth grade, and he had problems with school achievement. The defendant served as a combat infantry soldier in both the Korean and Vietnam wars. He completed one tour in Korea and three tours in Vietnam, where he earned a Bronze Star and Purple Heart. During his tours of duty, he suffered severe traumatic stress including being shot at, witnessing people getting killed, killing others in the line of duty, and experiencing traumatic brain injury. The veteran did not receive any assessment or treatment for his PTSD during either war.

When he returned to the United States, he had florid PTSD symptoms and evidence of domestic violence with his wife and extreme difficulties with chronic intrusive memories, flashbacks, and nightmares. He worked as a security guard in a prison where he experienced further trauma and multiple concussions. He qualified for a dual-diagnosis condition as he became an alcoholic when returning from Korea and was chronically drinking until age 65 when finally, he gained sobriety. He received full disability from the VA for PTSD and other medical conditions.

The neuropsychological assessment conducted indicated mild to moderate neurocognitive deficits in several areas including memory, executive functioning, and attention. He qualified for evidence of PTSD, major depressive disorder, and mild to major neurocognitive disorder due to traumatic brain injury and other vascular medical risk factors, as well as the chronic effects of alcohol use on brain functioning.

The court requested a 702 hearing, and the author testified in this hearing that the defendant was suffering from severe PTSD and a mild to moderate neurocognitive disorder due to traumatic brain injuries and a dementing condition as well as an early neurodevelopmental disorder, and further, that these conditions ultimately affected his mental state at the time of the offense, particularly regarding a self-defense claim.

The trier of fact then must consider evidence relevant to the same circumstances of the actor. Accordingly, the trial court found this author’s testimony admissible as applied  to the defendant and agreed that despite the ordinary person standard, the jury should be allowed to specifically hear testimony as to the same circumstances as the actor (defendant’s mental, psychiatric, and neuropsychiatric conditions, evidence of psychiatric symptoms and brain dysfunction that included executive functioning impairments pertaining to problem solving and impulse control ultimately detrimentally impacting his fight/flight response system). 


Under Texas Penal Code § 8.01, “it is an affirmative defense to prosecution that, at the time of the conduct charged, the actor, as a result of severe mental disease or defect, did not know that his conduct was wrong.” The term “mental disease or defect” does not include an abnormality manifested only by repeated criminal or otherwise antisocial conduct.”12

In Texas, the wrongfulness standard is typically a cognitive knowing standard and does not include the emotional and affective standard used in federal insanity law. Regarding the latter, the Insanity Defense Reform Act (IDRA) of 1984 reads, “at the time of the commission of the acts constituted in the offense, as a result of a severe mental disease or defect, they were unable to appreciate the nature and quality or wrongfulness of their acts.13 This statute does have some potential consideration of affective and emotional states related to mental illness and does remove the volitional component that the American Law Institute (ALI) insanity defense has regarding the defendant lacking the capacity to conform their conduct to the law.14 Both the IDRA and ALI insanity tests open the door to emotional and volitional issues that the typical cognitive “knowing wrongfulness” test lacks.

Due to the narrow cognitive knowing of wrongfulness test, it is difficult to prevail on many insanity defense cases. Typically, an individual who does not know right from wrong will be in a psychotic, manic/psychotic, or demented mental state at the time of the offense. Concerning PTSD, if an individual is in a profound dissociative state with potential evidence of depersonalization and/or derealization, there may be a better chance for an insanity defense. When an individual is dissociating and has recurrent feelings of being detached and dissociated from one’s body mind processes, usually with the feeling of being outside of themselves, including being an observer of one’s life or being detached from one’s body/mind feelings and/or sensations, they may have a compromised capacity in knowing the wrongfulness and illegality of their offenses. 

Depersonalization is when an individual feels detached from one’s body, mind, feelings, and/or sensations, while derealization occurs when an individual feels detached from their surroundings, such as people, objects, events, and they perceive things as being unreal. When these two symptom clusters of depersonalization and derealization occur together the individual may feel detached from their own self and perceive that things are unreal. These severe dissociative traits are close in replica of a psychotic disorder such as schizophrenia in which an individual has hallucinations or delusions and they lack contact from reality. In essence, the symptoms of depersonalization and derealization may lead an individual to not perceive that they are in contact with reality. Further, in many cases of PTSD, the defendant will suffer from other psychiatric disorders and/or TBI which may have a cumulative effect with the PTSD symptoms on their overall functioning and capacity in knowing the wrongfulness of their acts.

In Kemp v. State,15 a Vietnam veteran shot his wife in bed and pled not guilty by reason of insanity. He stated that he was dreaming of being surrounded by Viet Cong, and this dreaming episode certainly would have been an intrusive symptom of PTSD. The defense did not prevail, and the defendant appealed. The Wisconsin Supreme Court ordered a new trial in the interest of justice on the single issue of the defendant’s special plea of not guilty by reason of insanity or lack of mental responsibility at the time of the act. The doctor called by the defendant and two court appointed witnesses all testified that the defendant was legally insane, and two doctors called by the state stated they could not form an opinion, while one doctor called for the state testified that he did not have an opinion but that maybe the defendant did lack mental responsibility. 

In cases like this, the most ideal insanity case with PTSD should include the defendant experiencing a dissociative traumatic type episode that is reminiscent of a prior trauma experience. A defendant who commits a violent act who is dissociating at the time of the offense would have an enhanced defense if he were perceiving a similar trauma that he had experienced before. In essence, the trauma at the time of the instant offense ideally will be reminiscent of the earlier trauma(s). 

In a case closer to home in the Lonestar State, American Sniper Chris Kyle was shot and killed by Eddie Ray Ruth. The defendant was a former Marine who had been given a diagnosis of PTSD and spent time in several hospitals being treated for mental illness and was even prescribed antipsychotic medication. Mr. Ruth also used a not guilty by reason of insanity defense. His defense included his portrayal of being in a psychotic episode when he shot and killed Kyle in Littlefield at a gun range in February of 2013. Ruth’s insanity defense failed, and he was sentenced to life in prison without parole. The failure of the defense was due in part to the defendant’s problems with drugs and alcohol and because the State’s experts opined that he was exaggerating mental illness during the examinations. 

Mitigation of Military and Civilian PTSD and TBI

Perhaps the most common process of utilizing forensic psychological and neuropsychological evidence of PTSD and TBI in military and non-military civilian cases is through mitigation evaluations/packages provided to the prosecution, court, and/or jury through forensic reports and/or testimony. Mitigating evidence about a defendant’s background, character, and characteristics of his offense is relevant because, pursuant to “evolving standards of decency” in our society, such factors speak to one’s moral culpability.16

Mitigation evaluations are utilized by the defense to provide the prosecution information outside of the criminal offenses and can be used to educate them as to the defendant’s background history, ultimately relating to moral culpability. These evaluations often assist the defense in the plea negotiation process. 

In the absence of specific direction and guidance from statutes or sentencing guidelines, numerous federal and state decisions have recognized PTSD as a mitigating factor when the offender is a military veteran. 

In Porter v. McCollum,17 the United States Supreme Court held that the lawyer’s failure to present evidence of PTSD connected to military service during the sentencing phase of a capital case constituted ineffective assistance of counsel. The Court emphasized the importance of recognizing the defendant’s service to his country, “Our nation has a long tradition of affording leniency to veterans and recognition of their service, especially for those who fought on the front lines.” The Court also associated the concepts of PTSD in military service, “the relevance of…combat experience…is that the jury might find mitigating the intense stress and mental and emotional toll that combat took on the offender.” Also emphasized, was the importance of the defendant’s military service as a part of a general policy relevant to leniency to war veterans while recognizing the psychological trauma stemming from combat experience, the latter which could have diminished the offender’s capacity to form the requisite intent in committing the crime. 

In the United States v. Brownfield,18 a federal judge in a non-capital case sentenced the defendant to five years of probation and ordered a psychiatric evaluation for a military-based PTSD condition and explained that the case involved issues the federal sentencing guidelines do not address regarding the criminal justice system’s treatment of returning veterans who have served in Afghanistan and Iraq. 

When considering non-capital federal cases, U.S.S.G. § 5K2.0 allows departure from the sentencing minimums for “extraordinary mental condition.” In federal court, diminished capacity is identified pertaining to a reduced sentencing under the federal sentencing guidelines rather than a formal defense during the guilt/innocence phase of a trial. According to the § 5K2.13 diminished capacity policy statement, it provides for a downward departure if: 1) the defendant committed the offense while suffering from a significantly reduced mental capacity; 2) the significantly reduced mental capacity contributed substantially to the commission of the offense.

Further, the advisory guidelines also note downward departure may be warranted based on military service, U.S.S.G. § 5H1.11-Military service may be relevant in determining whether a departure is warranted, if the military service, individually or in combination with other offender characteristics, is present to an unusual degree and distinguishes the case from the typical cases covered by the guidelines. A downward departure may be pursued pertinent to mental and emotional conditions, U.S.S.G. § 5H.13. According to § 5H.13, mental and emotional conditions may be relevant in determining whether a departure is warranted, as such conditions, individually or in combination with other offender characteristics, present to an unusual degree and that distinguish a case from the typical cases covered by the guidelines. In certain cases, downward departure may be appropriate to accomplish a specific treatment purpose (this could be related to a veteran obtaining specialized PTSD and/or TBI veteran-based treatment). Mental and emotional conditions could be relevant in determining the conditions of probation with supervised release; e.g., participation in a mental health program. Therefore, there are different avenues in federal court to argue downward departure pertaining to special veteran circumstances. 

When returning veterans with no prior criminal history run afoul of the law federal judges have the power pursuant to 18 U.S.C. §3553(a) to structure sentences that facilitate rehabilitation and reintegration.

In United States v. Cantu,19 the Ninth Circuit held that combat-related PTSD was the type of “mental condition” that would qualify a defendant for a downward departure for “diminished capacity” under U.S.S.G. §5K2.13. The Ninth Circuit had little difficulty concluding that PTSD is a qualifying disorder for “diminished capacity”:

Cantu’s post-traumatic stress disorder is a grave affliction. Its effect on his mental processes is undisputed. He has flashbacks to scenes of combat. He suffers nightmares, intrusive thoughts[,] and intrusive images. He is anxious, depressed, full of rage, markedly paranoid, and explosive at times.

The psychologist’s report shows that Cantu’s condition interfered substantially with his ability to make reasoned decisions, causing him to fixate on weapons and rely on them for feelings of personal safety and security. Cantu’s impairment is more than sufficient to make him eligible for a reduction in sentence under §5K2.13.20 The Court went on to explain that “the disorder need be only a contributing cause, not a but-for cause or a sole cause of the offense.” This policy statement, since amended, now requires that the disorder “substantially contribute” to defendant’s commission of the offense. If a departure is warranted under this policy statement, the extent of the departure should reflect the extent to which the reduced mental capacity contributed to the commission of the offense.

This author examined a defendant who was charged in federal court with multiple counts of  bank robbery. The defendant graduated from college and served as a front-line medic in the military and experienced/witnessed profound war related trauma, IED blasts, murders, killings, and earned numerous decorated medals from his service in Afghanistan and Iraq. When he returned to the United States, he experienced profound PTSD, major depression, and an inpatient psychiatric hospitalization. He exhibited significant neuropsychological impairments despite strong verbal and overall IQ scores. He became addicted to opiates, alcohol, and cannabis in addition to his impairments due to PTSD. He also had a history of concussions pre-dating his military service. 

Case Study

The defendant went on a bank robbery spree and described his motive as to achieve a euphoria and “wanted to feel something” like he felt in Iraq. He did not appear to be planning the offenses, but his motivation was again to achieve a sense of euphoria and rush. There was a disconnect between his emotions, thoughts, and behaviors, which certainly was related to his chronic PTSD condition. 

When holding up the bank tellers he lacked an appreciation as to how his behaviors affected others as he focused only on the stimulating, arousing, and inebriating effects that his actions had on him. He had a gun in the bank and said, “It did not seem like a gun or weapon…it was a like a TV remote…I was programmed to not feel emotion due to my war experiences…I eventually did not feel anything…I never considered what I did was really terrorizing anyone.” His impaired ability to feel, regulate, and process his emotions probably led to a diminished empathy for the victims and deficits in feeling remorse as well as a compromised ability to appreciate the severity and consequences of his behaviors. 

While he understood the wrongfulness of his behaviors, he had difficulty appreciating the quality of his behaviors pursuant to the Federal Insanity Defense Reform Act (IDRA). In particular, he lacked an emotional appreciation of how his behaviors were affecting others. The defendant had suffered from flashbacks involving alteration of consciousness, and he believed he was re-experiencing a traumatic situation when he was committing the bank robberies. These flashbacks, along with nightmares and intrusive memories, led to heightened emotional stress and to low autonomic activity.

While the defense did not raise an insanity defense, they did focus on his PTSD, major depressive conditions, and the neurocognitive deficits from the PTSD condition that placed him at risk for a diminished ability to choose and completely refrain from his behaviors. He was stimulation-seeking, reckless, impulsive, and found himself escalating these behaviors in frequency closer in time to the arrest. 

Despite his intelligence, the veteran’s PTSD condition had altered the functional and neural circuitry of his brain. The neuropsychological assessment revealed significant attention, memory, and executive deficits leaving him impulsive, seeking sensation and intense adrenaline producing experiences with deficits in regulating behavior and appreciating the consequences of his behaviors onto others.21

This defendant was experiencing heightened emotions, including anxiety, fear, guilt, depression, anger, shame, and he would suffer acute emotional reactions when he was exposed to reminders of his wartime traumatic events. Consequently, he utilized drugs to combat and self-medicate these negative emotions focusing his use on opiates to numb his hyper-aroused and traumatic states. 

Ultimately, under USSG § 5K2.0 federal law allows departure from the sentencing minimums for “extraordinary mental conditions.”22 The federal district court recognized this forensic psychological and neuropsychological data in the form of a sentencing mitigation package and sentenced him to 108 months despite him committing up to 12 bank robberies within a six-week span.

Brief Neuroscience Admissibility Issues

Forensic psychological and neuropsychological assessment, the specific testing and results, and testimony related to forensic legal issues such as first phase mental state evidence and mitigation are typically admissible. Courts will admit evidence deemed “relevant” as defined by Texas Rule of Evidence 401, which states that “Relevant evidence” means evidence having any tendency to make the existence of any fact that is of consequence to the determination of the action more or less probable than it would be without the evidence. However, Rule 403 allows a trial court to exclude relevant evidence if its probative value is substantially outweighed by the danger of unfair prejudice, confusion of the issues, misleading the jury, or by consideration of undue delay, waste of time, or needless presentation of cumulative evidence.

Although forensic psychological and neuropsychological assessment techniques themselves are typically admitted, the application of psychiatric diagnosis, functional neuropsychological and psychological impairments and symptoms, and their relationship to mental state evidence obviously can be contested by legal parties. The defense must be clear in a 702 hearing how mental health evidence, especially diagnostic symptoms and functional impairments, relate to the specific legal issue(s) in mind such as negating intent related to mens rea and diminished capacity or the standard of ordinary person in a self-defense claim. There should be a nexus between the diagnostic symptoms, functional capacity and impairments, and the law. 


While there appear to be more objections to the admissibility of neuroimaging cases in criminal court, neuroimaging evidence can be considered in both PTSD and traumatic brain injury. Neuroimaging in non-murder cases may not be as technically specific and intricate as in murder and death penalty cases in large part due to cost and funding. The most useful neuroimaging techniques include voxel-based morphometry (VBM) (volumetric MRI) functional magnetic resonance imaging (fMRI), PET scan, and diffuse tensor imaging (DTI). 

In its basics, neuroscientists can measure focal brain volumes with VBM which is an MRI technique that allows for the investigation of focal differences in brain anatomy.23 Essentially, a brain’s image is divided into hundreds of thousands of cubes, and a computerized algorithm quantifies total brain tissue, including gray and white matter and water. The individual’s brain data is then statistically compared with data derived from normal control subjects without neurological and psychiatric disorders and impaired cube brain tissue data. 

With DTI, this is an MRI neuroimaging technique examining the location, orientation, and variations in the brain’s white matter tracts which is important in examining how critical areas of the brain are interconnected. The DTI specifically looks at brain fiber tracks and neural circuitry that connects a variety of brain regions and offers data as to the integrity or damage of these fibers.24  These brain fiber tracks are needed in processing and communicating information to other areas of the brain.

fMRI is an imaging tool for determining which regions of the brain are working, their efficiency by detecting changes associated with cerebral blood flow, especially during cognitive tasks. 

PET scan is a neuroimaging test that includes the use of tracers which are attached to compounds such as glucose which is the main fuel of the brain. The PET scan can detect which areas of the brain are utilizing glucose at the highest rates and which ones are deficient or impaired.25

There are a number of studies addressing the neuroimaging in posttraumatic stress disorder.26 These studies have indicated the amygdala, hippocampus, and medial prefrontal cortex, including the anterior cingulate in PTSD. These areas of the brain are critical for emotional and fear/threat processing, paranoia, traumatic memories, planning, decision making, processing of emotions, and language for example. It is these areas that are often victimized by traumatic brain injury especially the prefrontal cortex, and there can be a double dose effect with a veteran or civilian with both PTSD and TBI. 

The trial court will often have a 702 hearing in which the forensic neuropsychologist will testify about the defendant’s background history, psychosocial and mental health background, the nature of the psychological and neuropsychological testing especially related to function impairments, as well as psychiatric diagnoses. The court will allow the forensic psychologist and neuropsychologist to testify about the defendant’s behaviors, including violence, as well as the forensic legal issues concerning the insanity, diminished capacity, mitigation, etc. The trier of fact may also allow the forensic neuropsychologist (not psychologist) to testify to neuropsychological testing data, brain behavior relationships, including the criminal and violent behavior, as well as the relationship between the neuropsychological testing results and the neuroimaging. The neuropsychologist can testify to not only the brain functions related to the tests themselves but also what regions of the brain the tests may measure. Similarly, the forensic neuropsychologist can testify to the connections between the neuropsychological testing results and to the neuroimaging results, as well as potentially to the psychiatric diagnoses and the neuroimaging results. 

Neuroscientific experts, such as neurologists, neuroscientists, and neuroradiologists will specifically be allowed to testify as to the neuroimaging process and results, as well as neuropathology, but courts often will not allow these experts to delve into criminal behavior or forensic issues as to insanity or diminished capacity. 

In a death penalty case this author examined, the defendant was a former police officer who served six tours as a civilian in a Middle East war zone where he suffered brain injury and later suffered from symptoms of PTSD. The defendant’s mental state deteriorated over time when returning to the United States on leave. He continued to become more impulsive and rageful in benign events, he misperceived threats, and was involved in a road rage incident. The other party to the road rage called the sheriff’s department who attempted to arrest the defendant following the road rage incident. The sheriff tried to gain entrance into the defendant’s home, and the defendant overreacted to his misperceived threat and shot and killed the sheriff.

The neuroimaging data indicated brain damage and shrinkage that could be a consequence of TBI, seizure disorder, PTSD, and/or delusional disorder. 

Psychological testing results yielded conditions consistent with clinical interview and background information relevant to PTSD and delusional disorder. Neuropsychological testing revealed evidence of significant brain dysfunction consistent with PTSD, traumatic brain injury, and an early dementing condition. There was a complete alignment between the structural neuroimaging data and the functional neuropsychological assessment data explaining an ultimate subcortical-cortical process of reactive aggression and violence. 

Essentially, the defendant was in a constant state of paranoia and misperceived threat, was impulsive and easily angered, and was cognitively deteriorating. He had a fight/flight condition regarding his brain neural circuitry and function. The forensic psychological and neuropsychological information and testimony was put forth in the mitigation phase of the court case rather than the guilt-innocence phase, ultimately yielding a life without parole outcome.  

Violence Risk Assessment and Risk Management

Veterans returning for war are at risk for criminal justice involvement, as well as trauma.27 Veterans with probable PTSD or TBI who reported anger and/or irritability are more likely to be arrested than other veterans, and they are at higher risk for aggression and violence. 

As part of a mitigation package, the defense may also request a violence risk assessment and risk management examination by the forensic psychologist/neuropsychologist. This violence risk assessment may be relevant to cases including other assault and violent non-murder cases. The forensic psychologist/neuropsychologist conducting risk assessment should certainly have a handle and experience relevant to the proper examination of violence risk assessment. 

A solid mitigation package is not only useful in figuring out and assessing what is wrong with the defendant, what psychiatric disorders they have, and how their brain is functioning, but also helpful on what to do with a defendant pertinent to risk management issues. Services and plans, living situations, personal and social support, as well as potential stressors need to be considered in this examination process. 

It is important to emphasize a focused and specialized risk assessment for violence with military veterans.28 Forensic evaluation should consider a dispositional, historical, clinical, and contextual risk factor analysis and assessment. 

Dispositional factors are basic demographics related to risk of violence and can include young age, male status, personality traits, aggressive attitudes, and low intelligence. 

Historical factors may include pre-deployment violence and criminal offenses, history of domestic violence, history of child abuse, witnessing domestic violence as a youth, dysfunctional family of origin, substance use, violent events experienced during deployment, and combat exposure.

Clinical factors can include PTSD and prior trauma, high PTSD symptom severity, TBI, substance use, low intelligence, depression, suicidality, and in particular the PTSD symptoms of irritability, low frustration tolerance, and hyperarousal. 

Contextual factors also may include single marital status, unemployment, financial difficulties, relationship problems, and newer marriages.

Treating the Veteran

There are a number of treatments to assist the veteran returning from combat. Obviously, there are a number of conditions to treat and especially are related to polytrauma (PTSD, TBI, chronic pain, and mental illness, especially major depressive disorder and substance dependence). Importantly, the potential of addressing impulsive aggression in treatment is critical through building emotional regulation skills with both individual and group therapies. Psychological treatment options may include skills, training, and affective interpersonal regulation, cognitive behavioral therapy, and dialectical behavioral therapy. Psychiatric medication management is often necessary to treat psychiatric and brain disorder symptoms affecting emotional, behavioral, and cognitive functioning.

Concluding Remarks

This article has addressed the unique issue of examining military motivated murder and violence. The information above in both Parts I and II, especially related to the assessment and diagnosis of PTSD and TBI, certainly can be applied to civilian cases, too. Further, the author cannot overemphasize the prevalence of early childhood trauma and the comorbidity of chemical dependency in military and civilian PTSD and TBI cases. 

Along these lines, this author sets forth a tri-diagnosis phenomenon that includes not only the typical dual-diagnosis and presence of psychiatric disorder and mental illness with chemical dependency and addiction, but as a third component of brain dysfunction, which often is present in these cases pertaining to traumatic brain injury and/or neurodevelopmental disorders present in offenders (early disorders of compromise in brain development, i.e., learning disorder, ADHD, intellectual disability, and autism spectrum disorder). 

The attorneys and court systems involved in these cases certainly have a heavy hand in dealing with such complexities in human behavior, brain behavioral relationships, and evidentiary tools such as neuroimaging when considering guilt, innocence, and moral culpability issues when working with these populations. 

In some Texas jurisdictions there are veteran treatment courts29 that allow for specialized handling for veterans involved in criminal court cases that consider coordinated systems of court supervised treatment that ensures accountability while empowering veterans to become an integral and productive member of their community. The veteran’s court dockets often provide programs that utilize evidence-based practices that assist veterans in getting mental health and chemical dependency treatment and vocation and employment training and experiences while providing risk management and rehabilitative efforts with an ultimate goal of preventing re-offending. 

The expert and lawyer should attempt to consult with the U.S. Department of Veteran Affairs and the Veteran’s Justice Outreach Program which is designed to avoid the unnecessary criminalization of mental illness and extended incarceration among veterans by ensuring that eligible, justice involved veterans have timely access to Veterans Health Administration (VHA) services. Veteran’s Justice Outreach specialists can provide direct outreach assessment and case management for justice involved veterans in local courts and jails and liaison with the local justice system partners.30 Along these lines, veteran treatment courts are another viable option to assess and monitor the criminogenic and mental health, as well as chemical dependency treatment needs for veterans involved in the criminal justice system. 

Imperative to assessment and management of risk is the consideration of the tri-diagnosis related to mental illness and frequently PTSD, major depression, with co-occurring substance dependence, and TBI. The potential mediating influence of substance use, mental health, and combat and other trauma experiences has significant implications for preventing criminal aggressive behavior among U.S. active duty military personnel.31

Ultimately, the Global War on Terrorism has had great consequences on the mental health of troops returning to the U.S. post-war service. The risk of experiencing psychiatric, neurological, and chemical dependency issues is profound and ultimately places the veteran in jeopardy of committing violent acts and landing in the criminal justice system. Proper forensic mental health assessment is vital for the best representation and equitable treatment of the veteran.


  1. Jackson v. State,  160 S.W.3d 568 (Tex. Crim. App. 2005).
  2. Lizcano v. State, 2010 Tex. Crim. App. Unpub. LEXIS 270.
  3. Ruffin v. State, 270 S.W.3d 586, 596-97 (Tex. Crim. App. 2008).
  4. Nikmanesh v. State, 2017 Tex. App. LEXIS 6051.
  5. State v. Perales, 2020 Tex. App. Lexis 75.
  6. Brown v. State, 2014 Tex. App. LEXIS 8189.
  7. RULE 702. TESTIMONY BY EXPERT WITNESSES.  A witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if the expert’s scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue.
  11. Broussard v. State, 809 S.W.2d 556, 559.
  14. United States v. Brawner, 471 F.2d 969 (D.C. Cir. 1972).
  15. Kemp v. State, 211 N.W. 2d 793 (Wis. 1973).
  16. Penry v. Lynaugh,409 U.S. 302 (1989).
  17. Porter v. McCollum, 130 S. Ct. 447 (2009).
  18. United States v. Brownfield, No. 08-cr-00452-JLK, slip op. at 28 (D. Colo. Dec. 18, 2008).
  19. United States v. Cantu, 12 F.3d 1506 (9th Cir. 1993).101.
  20. United States v. Cantu, 12 F.3d 1513 (9th Cir. 1993).
  21. Horner, M., & Hamner, M. (2002). Neurocognitive functioning in posttraumatic stress disorder. Neuropsychology Review, Vol. 12(1). Vasterling, J., et al. Attention, learning, and memory performances, and intellectual resources in Vietnam veterans: PTSD and no disorder comparisons. Neuropsychology, Vol. 16(1).
  23. Voxel-Based Morphometry.  Voxel based morphometry (VBM) is a technique using MRI that allows investigation of focal differences in brain anatomy, using the statistical approach of parametric mapping.   Handbook of Clinical Neurology.  2014.
  24. Alexander, Andrew L; Lee, Jee Eun; Lazar, Mariana; Field, Aaron S.  Diffusion Tensor Imaging of the Brain.  An introduction to fMRI.  April 2015.  doi:  10.1007/978-1-4939-2236-9_5.
  25. PET Imaging in Neurology. Karl F. Hubner Department of Radiology, University of Tennessee Medical Center, Knoxville, Tennessee.
  26. Bremner, M.D., J. Douglas.  Neuroimaging in Posttraumatic Stress Disorder and Other Stress-related Disorders.  Neuroimaging Clin N Am. Author manuscript; available in PMC 2009 Aug 19.  Published in final edited form as:  Neuroimaging Clin N Am. 2007 Nov; 17(4): 523–ix.  doi: 10.1016/j.nic.2007.07.003.
  27. Elbogen, EB & Johnson, Sally.  Criminal Justice Involvement of Trauma and Negative Affect in Iraq and Afghanistan War Era Veterans.  Journal of Consulting and Clinical Psychology.  (2012) Vol. 80, No. 6, 1097–1102.
  28. Elbogen, Eric B.; Fuller, Sara; Johnson, Sally C.; Brooks, Stephanie; Kinneer, Patrick; Calhoun, Patrick S.; Beckham, Jean C.  Improving Risk Assessment of Violence Among Military Veterans:  An Evidence-based Approach for Clinical Decision-making.
  31. Hourani, Laurel L.; Williams, Jason; Lattimore, Pamela K.; Trudeau, James V.; Van Dorn, Richard A.  Psychological Model of Military Aggressive Behavior: Findings From Population-Based Surveys.
John Matthew Fabian
John Matthew Fabian
John Matthew Fabian is a board-certified forensic and clinical psychologist and clinical neuropsychologist. His Texas-based practice performs evaluations nationally for cases involving competency, insanity, self-defense, death penalty, and juvenile homicide, among other issues. Dr. Fabian has also worked as a clinical neuropsychologist at the University of New Mexico School of Medicine Center for Neuropsychological Services and Veteran’s Administration Polytrauma Traumatic Brain Injury and PTSD Unit and regularly conducts forensic neuropsychological evaluations with both active duty military and veterans. He can be reached at and 512-487-7216 and 216-338-6462.

John Matthew Fabian is a board-certified forensic and clinical psychologist and clinical neuropsychologist. His Texas-based practice performs evaluations nationally for cases involving competency, insanity, self-defense, death penalty, and juvenile homicide, among other issues. Dr. Fabian has also worked as a clinical neuropsychologist at the University of New Mexico School of Medicine Center for Neuropsychological Services and Veteran’s Administration Polytrauma Traumatic Brain Injury and PTSD Unit and regularly conducts forensic neuropsychological evaluations with both active duty military and veterans. He can be reached at and 512-487-7216 and 216-338-6462.

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