SEATTLE - For the second day, the mother of the accused Seattle Pacific University shooter took the witness stand.

Janice Ybarra described her son Aaron's delayed development and his obsessive-compulsive disorder.

She described a time when one of his brother's friends stole cologne from Aaron, and Aaron was obsessed about it for months.

"Aaron was extremely upset about the missing cologne. He just talked about it. He hated the person," she said. "It was continuing conversation that he wouldn't let go."

She recounted how Aaron started drinking more when he turned 21. His dad was out of jail, and he would go to the bar with his dad.

She also told a heartbreaking story about when her husband was in jail for a DUI and her younger son was addicted to heroin. She said her younger son's friends were living in the home, stealing thousands of dollars in valuables from her to pay for drugs.

Aaron Ybarra faces first-degree murder and attempted murder charges for the 2014 shootings on the SPU campus that left one dead and two others injured.

On Wednesday, jurors made a field trip to the shooting scene at Otto Miller Hill on the SPU campus. The prosecution hoped to show how small the hall is and how personal it was for students who were shot that day.

The trip to campus was quick, only 15 to 20 minutes, and jurors were not allowed to say a thing while at the crime scene.

The prosecution rested their case on Wednesday, and the defense started on Thursday with testimony by Ybarra's mother. The defense is not denying anything, simply saying Ybarra is not guilty by reason of insanity.

Ybarra's attorney confirmed Thursday he's expected to take the stand on Monday.

Watch: SPU shooting trial jurors take field trip to the scene

KING 5's Elisa Hahn is covering the latest developments in the trial, which is expected to last for several months. (For app users, read her updates on Storify here.)