Thoughts of killing other people became an uncontrollable storm in the mind of the Colorado theatre shooter in the months before the attack, a nationally known schizophrenia expert testified Tuesday.
James Holmes experienced fleeting thoughts about homicide previously, but he always found refuge in computer games and homework, said Dr. Raquel Gur, head of neuropsychiatry at the University of Pennsylvania medical school.
But after Holmes enrolled in a doctoral neuroscience program at the University of Colorado in 2011, the power of those thoughts "was in some ways like a storm," Gur testified.
Gur said Holmes suffered from schizophrenia at the time of the crime, and she is expected to say she believes he was legally insane when he killed 12 people and wounded 70 during the July 20, 2012, attack on a suburban Denver movie theatre.
Her testimony is crucial as defence attorneys argue that during the shooting, Holmes was in the grips of a psychotic episode that rendered him unable to tell right from wrong — the threshold for an insanity verdict in Colorado.
"I agree, there wouldn't have been a shooting at all" if Holmes hadn't suffered from a psychotic disease, Gur told defence attorney Daniel King.
Prosecutors say he was sane and are seeking the death penalty.
Gur said she repeatedly asked Holmes why he did not kill himself instead of others, and he replied that he couldn't bring himself to do it.
When she asked him how he thought the victims and their families would feel, he was shocked.
"It was something that he did not consider," she said.
Gur interviewed Holmes for 28 hours over two years and studied the spiral notebook in which he scrawled elaborate plans for the massacre.
Gur also has evaluated Unabomber Ted Kaczynski and Jared Loughner, who killed six people and wounded 13 more near Tucson, Arizona, in 2011.
She said Holmes is philosophical and highly intelligent, similar to Kaczynski.
"The higher functioning people, namely those who have greater intellectual capacity, are the ones who come up with the most bizarre delusions," she said.
An MRI done earlier this year showed parts of Holmes' brain that affect emotional response were smaller in volume than those of a healthy brain, possibly affecting his ability to make rational decisions, Gur said. Throughout her conversations with Holmes, he seemed flat and emotionless, a possible indicator of schizophrenia.
Of the doctors who examined Holmes for the defence, Gur spent the most time with him and interviewed his parents.
But her testimony will be highly contentious. Prosecutors spent nearly two days tearing apart the testimony of another psychiatrist who said he found Holmes was insane.
Gur's findings also differ from those of two court-appointed doctors who studied Holmes in the months and years after the shooting and found him legally sane at the time of the attack.
This content appears as provided to The Globe by the originating wire service. It has not been edited by Globe staff.