RICHARDSON -- The Richardson shooting suspect police say killed an officer and a 30-year-old man Wednesday night had been acting strange in the past few months, WFAA has learned from a source close to the investigation.

On Aug. 21, the sister-in-law of Brandon McCall, 26, called Dallas police and said he was feeling paranoid and thought someone was following him. He also wanted to jump off a bridge on Preston Road and was talking to himself, the source told WFAA's Tanya Eiserer.

Veteran Richardson police officer David Sherrard was killed in the line of duty Wednesday, Feb. 7, 2018.

McCall also threatened to open a car door while it was moving that night, and when officers investigated, he told them he wanted to be put to "sleep permanently," the source said.

He then underwent a mental evaluation at a local hospital.

On Wednesday, McCall became involved in a standoff with police officers at the Breckinridge Point Apartments after reportedly shooting Richardson Police Officer David Sherrard, a 13-year veteran of the department, and 30-year-old Rene Gamez. Both men died.

Rene Gamez (GoFundMe)

After five hours, McCall surrendered to police. He's been charged with capital murder.

Before Wednesday, nothing in McCall’s criminal history would have signaled what was to come. In 2009, he was twice arrested for misdemeanor marijuana possession in Dallas County. He received deferred probation for both charges.

The next year, Garland police arrested him on an unauthorized use of a motor vehicle charge. No case file has been found for that incident.

In 2016, Richardson police arrested him on a felony possession of cocaine charge. He received two years deferred probation from a Collin County court. It was scheduled to end next year.

The lawyer who handled that case declined to comment.

Around the apartment complex, neighbors said they had seen McCall, but they never noticed anything out of the ordinary with him before the night of the deadly standoff.

“I’ve just seen him going back and forth to the trash,” said Charlie Ray, who lives in the complex. “Everybody just sees everyone. They say hi and go on about their way."