A federal trial for the man who fatally shot 11 people at a Pittsburgh synagogue approached its conclusion Friday as the defense, trying to persuade a jury to spare his life, pressed its case that mental illness spurred the nation’s deadliest antisemitic attack.

Robert Bowers, a 50 year-old truck driver from suburban Baldwin, was convicted in June on 63 criminal counts for the 2018 massacre at Tree of Life synagogue. The jury has been hearing testimony in the penalty phase of the trial and will decide whether Bowers will receive the death penalty or life in prison without parole.

Prosecutors have presented evidence that Bowers was motivated by his hatred of Jewish people when he opened fire at the synagogue on Oct. 27, 2018, killing members of three congregations gathered for Sabbath worship and study. The defense argues Bowers has schizophrenia and acted out of a delusional belief that Jews were participating in a genocide of white people.

On Friday, a defense psychiatrist who met with Bowers 10 times for nearly 40 hours said Bowers saw himself as a soldier of God in a war in which Satan was trying to use Jewish people to bring about the end of the world. Dr. George Corvin, of Raleigh, N.C., said it was a delusion brought on by psychosis.

Corvin said Bowers continues to express delusional beliefs about Jews — “disgustingly so” — and that he is incapable of remorse. He said Bowers should be on anti-psychotic medication.

Bowers “has a belief that we’re at the end of a war that’s been going on for thousands of years,” Corvin testified. “He still envisions what he did as an unfortunate act of violence at the direction of God — that it will save lives. He believes he’s a tool for God. I know it sounds absurd. It’s psychotic.”

Corvin continued: “This is the result of a mental illness.”

Corvin was one of several defense experts who diagnosed Bowers with schizophrenia, a serious brain disorder whose symptoms include delusions and hallucinations. A neurologist testifying for the prosecution disputed that Bowers has schizophrenia, saying Bowers has a personality disorder but is not delusional, and that mental illness did not appear to play a role in the attack. Prosecutors have noted Bowers spent six months planning the shooting.