An Iraq War veteran on trial for allegedly killing his ex-girlfriend’s father last year took the stand in his own defense Monday in Solano County Superior Court.

Robert J. Vega, 32, of Fairfield is charged with murder and kidnapping.

Vega allegedly shot and killed off-duty Richmond Police Officer Augustine “Gus” Vegas inside his Glencove Vallejo home in the early morning hours of Feb. 11, 2016.

“I was in pain,” Vega said Monday.

Vega, who revealed he had hoped of getting back together with Angel Vegas, the mother of his 6-year-old son, stated he wanted to talk to her that night, though she told him she wanted to talk in the morning. Eventually, Vega grew angrier, touting his pistol firearm, and screaming at the top of his lungs to wake everyone in the house up.

When Gus Vegas opened the bedroom door and entered the room, Vega said his memory is spotty.

“I looked him in the eyes,” he said. “I blacked out after that.”

Vega testified he felt Vegas posed a threat to him in that moment.

“I thought he came in to kill me, and that my life was in danger,” he revealed. “I reacted in self-defense.”

Though not together at the time of the shooting, the Vega and Angel maintained a cordial co-parenting relationship, with Vega even staying over at the Vegas’ residence the two nights leading up to the shooting.

Vega was invited by Angel to stay at her parents’ home after he told her his neighbors at his Grande Circle apartment in Fairfield were talking about him. Angel claims she noticed the defendant acting differently about a month before the shooting.

Vega, a United States Army veteran who served in Iraq following his graduation from high school in 2003, was diagnosed with post-traumatic stress disorder after he returned home from the war, according to court discussions.

Vega, also testified he never killed anyone in Iraq, and didn’t participate in any firefights.

The day of the shooting, Vega was allegedly sleeping upstairs in the Vegas home with his son when Angel returned home from work around 4 a.m.

In her testimony last week, Angel said Vega continued his odd behavior, talking about God and love, even dropping down to his knees in prayer at one point.

Vega ultimately fired eight shots in total into Vegas before taking his son with him and fleeing to his Fairfield apartment, where he was arrested upon arrival.