The two officers killed on a Brooklyn street were not Ismaaiyl Brinsley's only victims. On Saturday he shot and wounded an ex-girlfriend in Baltimore, then hopped a bus to New York, where he later carried out the murders. He was no stranger to trouble.

Ismaaiyl Brinsley's criminal past went back more than a decade. From August, 2004 to June, 2013 he was arrested in Georgia at least 15 times for assault, shoplifting and grand larceny. He was also arrested four times in Ohio in 2009. Beginning in 2011, he served two years in prison for criminal possession of a weapon.

He had been estranged from his family for years, today his sister Jalaa'a Brinsley spoke.

"It had nothing to do with police retaliation. Absolutely nothing to do with police retaliation," she said. "He was disturbed. The way he did this was horrifying."

Brinsley was originally from Brooklyn. His mother told police she feared her son. She said he had a troubled childhood and was often violent. Investigators found 119 items on his Instagram account filled with self-despair and anti-government views.

"If you have emotional issues, and you're constantly going in and out of jail, prison and clearly something is wrong, he should have been offered help," said his sister.

Ismaaiyl Brinsley had a lengthy criminal history and struggles with mental illness, his family says. CBS News

Brinsley's family told investigators he tried to kill himself a year ago. On Saturday morning, before he left Baltimore, his ex-girlfriend told police she talked Brinsley out of another suicide attempt.

"He put the gun to his own head when he broke into her apartment," said Baltimore Police Chief Robert Boyce. "And then she talked him out of that, and he later shot her before he left."

Investigators are trying to piece together what Brinsley was doing in the two hours before the officers were killed. They believe he acted alone, but want to know if he talked to anyone about his plans. They will also look into where Brinsley was and who he communicated with in the 10 days before the shooting.