James Holmes’ father took the stand Tuesday in the Aurora theater shooting trial, describing his son -- who could face the death penalty for killing 12 people at a crowded midnight movie premier in 2012 -- as an easy going kid who liked video games.

"He never required much in the way of limits in terms of staying out late, personal behavior, other than video games, and making sure he did his chores," Robert Holmes testified. "He was pretty easy to deal with."

Attorney Tamara Brady led the questioning.

"Do you still love him?" she asked Robert Holmes.

"Yes, I do," he replied.

"Why?"

"Well he’s my son and we always got along pretty well, and he was always, he was actually, really, an excellent kid," Robert Holmes said.

The father mostly referred to his son as Jimmy during testimony. He said he thought his son could have been depressed before the shooting, having recently broken up with his girlfriend and dropped out of graduate school. But when the family learned there was a shooting, Robert said he though James must have been a victim, not the gunman.

The attorneys also played a voice message from father to son sent a month before the shooting.

"Hi Jim this is Dad, I was just calling to find out how everything is going there," Holmes' father says on the recording. "Kind of miss you here, and we’re hoping to sort of stay in touch, we haven’t heard too much from you recently."

When asked if James seemed like himself immediately after the shooting, Robert Holmes replied, "No, he seemed, clearly, really messed up."

Robert Holmes has attended every day of his son's trial along with his wife, Arlene, but this is the first time he has testified. Robert Holmes said he didn't know his son was mentally ill before the July 20, 2012, attack.

He also said he didn't know much about his family's history of mental illness until investigators researched it for the trial. He acknowledged that his parents didn't talk about their emotions.

The father's appearance was part of a strategy by Holmes' attorneys in this sentencing phase of the trial to try and humanize their client. Still, neither Robert Holmes nor his son smiled at each other in court. And Arlene Holmes, seated two rows behind her son, hasn't visibly reacted to photographs and videos showing her family's holiday gatherings, soccer games and trip to Disneyland.

Some of the images have elicited chuckles from the courtroom but not from the victims' portion of the gallery. Unlike previous days, it is largely empty.

Robert Holmes is expected back on the stand Wednesday for cross examination by the prosecution. Arlene Holmes is also expected to testify soon.

The Associated Press contributed to this report.