Background
In February 2022, Kirk Glenn Reiber visited a 24-Hour Mobile Truck & Trailer Repair shop and asked the owner to repair a flat tire on his bicycle. The owner declined, and Reiber left but returned approximately thirty minutes later demanding the repair. After being told to leave, Reiber complied, but later that evening the shop owner discovered his service truck was missing.
The next day, when the owner’s son confronted an individual attempting to operate a customer’s car hauler truck on the property, Reiber—who was driving—put the vehicle in reverse and accelerated at high speed. The truck struck and dragged the shop owner’s wife approximately 20 to 30 yards, causing her a concussion and a torn labrum. Police arrived and arrested Reiber at the scene. A jury convicted Reiber of two counts of unauthorized use of a vehicle and one count of aggravated assault with a deadly weapon.
The Court’s Holding
The trial court sentenced Reiber to twenty years imprisonment on each unauthorized use conviction and life imprisonment on the aggravated assault conviction after finding two felony enhancement paragraphs true. On appeal, Reiber challenged the legal and factual sufficiency of evidence supporting the jury’s rejection of his insanity defense. The Court of Appeals affirmed the convictions in all respects.
The court emphasized that insanity is an affirmative defense placing the burden of proof on the defendant, who must prove it by a preponderance of the evidence. Critically, the court held that expert psychological testimony—even if uncontradicted—does not establish insanity as a matter of law. Juries remain the ultimate arbiters of whether a defendant understood his conduct was wrong; they may reject expert opinion, weigh it against lay testimony and circumstantial evidence, and reach their own conclusion on the legal question of insanity.
The court found sufficient evidence supporting the jury’s verdict. Reiber’s attempt to flee when law enforcement was contacted suggested knowledge that his conduct was illegal. Similarly, evidence that Reiber attempted to pry open the service truck indicated he knew he lacked permission to use it. The jury could reasonably conclude that Reiber’s impersonation of a shop worker—claiming employment at the repair facility to gain access to the customer’s vehicle—was deliberate deception rather than confusion caused by mental illness. The jury was also entitled to credit the responding officer’s on-scene observations of Reiber’s demeanor over the defense expert’s evaluation, which occurred more than a year after the incident.
Key Takeaways
- Insanity is an affirmative defense; defendants bear the burden of proving it by a preponderance of the evidence.
- Expert psychiatric or psychological testimony, even if uncontradicted, does not establish insanity as a matter of law—juries may reject or discount such testimony in favor of lay evidence and circumstantial facts.
- Evidence of flight or attempts to conceal or gain access to property without permission can support an inference that a defendant understood his conduct was illegal, defeating an insanity claim.
- Juries may credit lay witness testimony and credibility assessments over expert opinions offered long after the events in question.
Why It Matters
This decision reinforces a critical principle in Texas criminal law: expert mental health testimony in insanity cases does not displace jury determinations of fact. While psychiatric evidence of mental illness is relevant and admissible, Texas law recognizes that insanity involves legal and ethical considerations beyond medical diagnosis alone. The jury’s constitutional role as fact-finder is protected from being usurped by expert opinion, no matter how qualified the expert or how uncontradicted the testimony.
For criminal practitioners, the decision clarifies that circumstantial evidence of knowledge of illegality—particularly flight, attempts at concealment, or deceptive conduct—can significantly undermine an insanity defense even where credible mental health evidence supports it. The decision also underscores the importance of developing lay testimony regarding the defendant’s demeanor and apparent understanding at the time of the offense, as such evidence may outweigh expert evaluations conducted months or years later.