Boise man with schizophrenia repeatedly stabbed a stranger. He’ll spend life in prison

Ruben Diaz, a Boise man with a long history of mental illness, was sentenced to life in prison without the possibility of parole for repeatedly stabbing a stranger in 2018 — the third time he’s attacked someone since 2006.

Just before Diaz was sentenced, 4th Judicial District Judge Jonathan Medema said there were two possibilities as to why he had repeatedly attacked people in his life: Diaz either liked hurting people, or he wasn’t able to control himself because of his schizophrenia, Medema told the courtroom.

“In the end, I’m not willing to risk that someone else will go through what three other people have gone through because Mr. Diaz chooses to stab people,” Medema said.

After a five-day trial in September, Diaz was found guilty of felony aggravated battery with a deadly weapon enhancement, of resisting or obstructing police and of being a persistent violator, despite the defense pointing to Diaz’s history of mental illness. The trial centered on Diaz’s mental health at the time of the crime.

In 2018, Diaz repeatedly stabbed a stranger, was arrested, charged and quickly found to be mentally unfit to stand trial. Diaz was diagnosed with schizophrenia and autism and was living in an assisted-living home at the time of the crime, the Idaho Statesman previously reported. His competency was restored in 2019.

When Diaz was off his medication, he’d threaten or attack people — something that Diaz and the Idaho Commission of Pardons and Parole were aware of, according to court records in previous Statesman reporting.

Diaz, now 40, was charged with a crime in 2006 after he walked up behind a man and stabbed him, and again in 2007 after he attacked his roommate with a sword and cut off his fingers, according to previous Statesman reporting. Both times, Diaz wasn’t taking his medication.

State law does not allow for an insanity defense. But the Idaho Supreme Court last year ruled that it was relevant to provide evidence about Diaz’s mental health during the trial. The justices allowed for expert testimony that said Diaz didn’t know his victim was human, because his mental illness caused him to believe he stabbed an alien, according to court documents.

Boise responding officers take the stand

Officer Brek Orton told a courtroom that in November 2018, he raced to respond to a dispatch call that reported a long-haired female was cutting off the head of someone in a southeast Boise driveway. Orton had expected to find someone in a mental health crisis, he told a jury.

Once Orton arrived on scene, on the 3000 block of South Preamble Place, he dispatched into the police radio, “Real incident, step it up everyone,” as he witnessed then-36-year-old Ruben Diaz repeatedly stabbing a 74-year-old stranger, Gary Vinsonhaler. The body camera footage was played for the jury during the five-day trial against Diaz in September.

Orton and Officer Jason Pietrzak from the Boise Police Department took the stand and retold the events of how they were involved in Diaz’s arrest. Diaz’s defense attorneys asked Orton, who was the first to respond to the scene, what he meant when he called it a “real incident.”

“We consistently get calls, whether they’re drug-induced or mental health crisis-induced, to where people will call, and they’re hallucinating or see different things,” Orton said.

Prosecutors question mental health evaluations

Prosecutors in the trial argued that Diaz had used claims about mental health in the past to manipulate his situations. When taken into custody the day of the attack, Diaz told an Ada County paramedic, John Pollock, that he was over-medicated and that was the reason he committed the crimes, prosecutors said, but there had been no record of Diaz being over-medicated.

Michael Sweda, a clinical and forensic psychologist and a witness for the prosecution, had interviewed Diaz in 2022 and inquired about his belief in aliens. From the interview, Sweda testified that the belief had originated in childhood and specifically from watching a conspiracy theorist who believed aliens reside on the moon craters and could invade human hosts by a worm-like appendage.

James Davidson, Diaz’s previous psychologist, had met with Diaz on multiple occasions before and after the incident. In one of those most recent visits on April 25, 2023, Diaz had told Davidson that he had believed Vinsonhaler was an alien when he attacked.

“Even when he was well-medicated, he acknowledged having thoughts about aliens, even though they were at a much lower level than other times when he was not appropriately medicated,” Davidson said.

The prosecution argued that Davidson was not a credible witness. Sweda told the jury that psychological assessments contained “red flags” that Davidson dismissed and instead had incorporated his own clinical opinion.

After reviewing his extensive history of mental psychiatric hospitalizations and mental health treatment tracing back to age 13, Sweda said there was no real dispute that Diaz had a mental illness.

“I’m not questioning his administration. It’s the interpretation that worries me,” Sweda said.

Diaz feels horrible, public defender says

When asked whether he’d like to make a statement to the court, Diaz said yes and immediately began to break down into sobs.

“I love people,” Diaz said through tears.

The prosecution and Diaz’s attorney disagreed about the role Diaz’s mental illness played in the crime. The prosecution argued the issue wasn’t about medication, and that Diaz was medicated during the attack because authorities had given Diaz an injection instead of oral medication that was stronger. Prosecutors asked Diaz to be sentenced to life in prison.

Diaz’s public defender Kate Enterkine asked Medema to sentence Diaz to up to 30 years in prison with the possibility of parole after seven years. Enterkine said Diaz experienced trauma throughout his childhood, and that there’s no question that Diaz’s mental illness played a factor in the crime.

“I know that he continues to feel terrible,” Enterkine said about Diaz. “I know that this is something that he doesn’t wish upon anyone. Obviously, ... this is not to the fault of Mr. Vinsonhaler at all.”

Medema said the voices in Diaz’s head may be compelling him to hurt people, and he’s not able to “engage the rational portion of his brain.” But he’s not sure that’s the case because Diaz behaves well while he’s incarcerated.

“The fact that he is able to resist acting on the voices while in prison certainly suggests that he simply chooses not to do so when he gets out — perhaps because he just likes hurting people,” Medema said. He said the fact that he wasn’t taking his medication after he was released from prison in 2018 also may have been a factor.

Boise police respond to scene

As of 2021, the Boise Police Department trains all their officers on critical incidents. But that wasn’t the case when Pietrzak interviewed Diaz in 2018.

Pietrzack during the trial said officers receive “very little” training from mental health professionals on how to interview suspects with mental illnesses.

The prosecution team asked Pietrzack whether this minimal training in how to interview suspects with mental illnesses resulted in him interviewing Diaz like he would interview any other suspect. Pietrzack said yes.

Boise Police Chief Ron Winegar told the Statesman that critical incident training had not been mandatory in 2018, and before that, it was optional for officers. Since 2021, new officers are required to complete 40 hours of crisis intervention team training, which teachers officers how to distinguish an incident involving mental health.

If somebody is suffering from bipolar disorder or schizophrenia, then officers have basic training on how to best reduce their fears while handling the crisis situation before taking them to the hospital, Winegar said.

The Boise Police Department’s Behavioral Health Response Team is currently made up of two mental health clinicians and two officers who rotate hours day in and day out, Winegar said.

“That’s really the goal, to deescalate the situation,” Winegar told the Statesman.