A truck driver facing the death penalty after being convicted of barging into the Pittsburgh Tree of Life synagogue was dismayed not to have inspired more attacks on Jews, a court has heard. 

Robert Bowers ran into the synagogue on October 27, 2018 and opened fire with an AR-15 rifle and other guns killing 11 congregants in an act of antisemitic terror.

The federal trial for Bowers approached its conclusion on Friday as the defence, trying to persuade a jury to spare his life, pressed its case that mental illness spurred the nation's deadliest antisemitic attack.

Dr George Corvin, a defence 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. 

Addressing a Pittsburgh court on Friday, Corvin said it was a delusion brought on by psychosis. 

pittsburgh shooter Robert Bowers

Robert Bowers (Photo: Butler County Prison)

He went on to say that Bowers expresses delusional beliefs about Jews "disgustingly” and that he was incapable of remorse. He stressed that Bowers should be on anti-psychotic medication.

Corvin testified: "Bowers has a belief that we're at the end of a war that's been going on for thousands of years”.

He added: “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. This is the result of a mental illness."

“Did he tell you he likes hearing the evidence?” US Attorney Eric Olshan asked him.

“Yes,” Corvin said. “I think he likes hearing the evidence so he knows other people can hear the evidence.”

Tree of Life Synagogue shooting

Mourners outside the Tree of Life Synagogue in Squirrel Hill, Pittsburgh after the shootings (Photo: Getty Images)

Corvin went on to explain that Bowers wanted others to emulate him and was disappointed that his mass killing still stands as the worst attack on Jews in US history.

“He hoped the act would bring attention to what he, quote, ‘knows,’ so more people would be inspired to protect God’s kingdom,” Corvin said.

Corvin was one of several defence experts who diagnosed Bowers with schizophrenia, a serious brain disorder whose symptoms include delusions and hallucinations. 

However, 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. 

The trial continues this week with closing arguments and jury deliberations.