The Pittsburgh synagogue shooter made several suicide attempts as a young man, was involuntarily committed multiple times and has schizophrenia and epilepsy, a neurologist who examined him testified at his death penalty trial Wednesday.

"He moves through the world not assessing the world correctly and under a sense, under a feeling, under a vague feeling of threat and paranoia," Dr. Siddhartha Nadkarni testified. "I think he has delusional beliefs. I don't think he's able to process or interpret information correctly."

The medical testimony came as defense attorneys make the case to the jury that Robert Bowers had significant mental health issues that should lead to a sentence of life in prison rather than the death penalty. The prosecution has countered by arguing the mass shooting showed extensive planning and a clear intent that, in his own words, "All Jews had to die."

Bowers, 50, was found guilty on June 16 of all 63 charges against him for killing 11 worshippers and wounding six others at Pittsburgh's Tree of Life synagogue in October 2018, the deadliest attack directed at Jewish people in the US.

Twenty-two of those counts were capital offenses, so he is eligible for the death penalty at this second part of the trial, known as the punishment phase. This portion of the trial is broken up into two parts: the eligibility phase, which was expected to last a few days, and the sentencing phase, expected to last four to five weeks.

The defense did not call any witnesses in the guilt phase of the trial, but they called four doctors to the stand on Tuesday. Nadkarni's testimony on Wednesday was the most detailed yet regarding Bowers' psychological issues, which dated to his childhood.

Nadkami testified that he "was asked to do a neurological evaluation of Mr. Bowers."

"(It's) very unusual to see such severe psychiatric history in a child," Nadkarni testified while examining his medical records. "He had something wrong going on with his brain at a very young age, that's what it made me realize."

Medical records from 1985 indicate Bowers "threatened to kill himself" at age 13 and had a "suicidal gesture" at age 10. He was involuntarily committed at age 16 and attempted suicide at age 17, the records show. He was committed in 1990 for repeated suicide attempts, according to a police report, and involuntarily committed again in 2004, the doctor testified.

"He has a very serious mental health history from a very young age," Nadkarni said.

In the evaluation, Bowers described instances of visual and audio hallucinations as well as panic attacks. He also said he had a belief system of ink being absorbed into his body, which Nadkarni described as a "profound delusion" that is associated with schizophrenia.

Bowers had issues with memory in his exam and failed a screening test in which he was asked to remember five basic objects after five minutes. However, he remembered rigid bits of information, such as numbers, dates, license plates and passwords, and was "almost obsessively focused on these things," the doctor testified.

He had poor eye contact and a flat and unreactive affect, very poor insight and judgment and trouble smelling different scents, Nadkarni testified.

"So many things in this exam point to front lobe and temporal lobe dysfunctions," he testified.