CENTENNIAL, Colo. >> James Holmes came home on winter break from graduate school looking haggard and making odd facial expressions, but his father didn’t suspect at the time that he was descending into mental illness.

"He was not a violent person. At least not until the event," Robert Holmes said.

"The event" is a phrase he used several times to refer to his son’s attack on the audience inside a darkened Colorado movie theater, which killed 12 people, injured 70 others and makes James Holmes eligible for the death penalty.

Months later, Robert Holmes said he recalled that look when his son flashed a wide-eyed smirk in a booking photo at the jail.

District Attorney George Brauchler pointed out while cross-examining Robert Holmes on Wednesday that the bug-eyed mugshot wasn’t taken immediately after his arrest, because his hair was no longer comic-book red.

Was he posing, perhaps trying to appear crazy? Robert Holmes deflected the prosecutor’s suggestion, saying he knew nothing about how the photograph was taken.

Their son did give them reason to worry in the months before the July 2012 attack, he said. They had rarely spoken by phone, but they communicated even less before his psychiatrist called them in June, saying he was dropping out of his prestigious neuroscience program.

"We didn’t know he was seeing a psychiatrist," Robert Holmes said. He and his wife thought then their son was depressed or suffering Asperger’s syndrome, but he said the doctor would not return their calls seeking more information.

Holmes did send his parents sporadic and terse emails that gave no hints of trouble, and their concerns were eased again when they finally reached him by phone on July 4, 2012, just two weeks before the shooting.

They spoke at length, Robert Holmes said. Their son was more talkative than usual and "he didn’t give any indication he was homicidal or depressed, at least not to us," Robert Holmes said.

They planned to fly from California for a visit in August. It would be too late. Instead, Robert Holmes booked a flight to see his son at his first court appearance, looking sullen and confused.

Defense attorneys will also call his mother, Arlene Holmes, to the stand as they prepare to rest their portion of the sentencing phase, which has included several dozen family friends, teachers and former neighbors who said the Holmes they knew was shy, mild-mannered and polite— not the kind of young man who would gun down innocent strangers.

Death sentences must be unanimous, and the judge has explained to jurors that their decision will be highly personal. While jurors have already found Holmes was legally sane at the time of the attack, his defense is hoping at least one juror will agree that his mental illness and family ties reduce his moral culpability so much that he deserves the mercy of a life sentence instead.

Jurors have been shown pictures and home-movies from Holmes’ unremarkable childhood: playing soccer, graduating high school, smiling at the dinner table, jumping in the surf near their quiet California neighborhood.

The father said his son was an isolated teen, who never brought a girlfriend home. His father rarely, if ever saw him with friends.

His parents were thrilled to learn he had started dating in graduate school, and knew it wasn’t a good sign when that first relationship ended, he said.

"We knew some things weren’t going well there," Robert Holmes said.

Brauchler sought to focus on what they didn’t know or didn’t tell jurors: that James Holmes’ mother took him to a counselor when he was just 8 because he was throwing things and acting out, and that once he was in college, he lost touch with his younger sister, and never inquired about her well-being.

During a break in testimony Wednesday, Robert Holmes motioned to his son and mouthed that they were wearing the same blue dress shirt. They both smiled before a deputy told the father to stop. Earlier in the trial, Arlene Holmes tried to pass a note to the defense table, but it was intercepted.

The father said that he has only seen his son in jail three times because he typically does not allow visitors. During a rare visit, James Holmes "was clearly really messed up," his father said. "But he told us he loved us."