(CNN) The mother of the man who killed two New York police officers has spoken out, apologizing for the horror her son Ismaaiyl Brinsley caused before taking his own life.

"Ismaaiyl was a very troubled young man whose life was in turmoil and spiraling out of control," Shakuwra Dabre said in a statement to CNN affiliate WABC

"We were estranged for a few years, with occasional contact. I am deeply sorry for the loss of the two innocent men who were killed, and offer my sincerest condolences to their families."

In an interview with the New York Daily News , Dabre said she was "horrified" when she found out what her son had done.

"And please accept my deepest condolences, sincerely. As a mother now I hurt for the loss of my son. Just like they're hurting for the loss of their sons," she said.

The families of police officers Wenjian Liu and Rafael Ramos are "suffering unspeakable pain," New York City Mayor Bill de Blasio said Monday. The two men were shot and killed in their car while on duty.

"Our first obligation is to stand by them in every way we can. And I call upon everyone to focus on these families in these next days."

Lucy Ramos, aunt of Rafael Ramos, thanked "all those who have shared their sympathy and support." Speaking Sunday night, she said her nephew " will always be loved and missed by many. I hope and pray that we can reflect on this tragic loss of lives that have occurred so that we can move forward and find an amicable path to a peaceful co-existence."

Outside Liu's home Monday evening, his widow thanked members of the community for their support and sent condolences to the Ramos family. "This is a difficult time for both of our families," Pei Xia Chen said, "but we will stand together and get through this together."

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The two had just been married in September.

Brinsley had a long rap sheet and struggled with mental illness.

In a 2011 hearing in Cobb County, Georgia, he pleaded guilty to theft, property damage, possession of a firearm by a felon and discharging a gun near a public street after he used a stolen .25-caliber handgun to fire into a gold Chevy Malibu.

When asked by a judge at the hearing whether he'd ever been a patient in a mental institution or under the care of a psychologist or psychiatrist, he answered yes, according to court documents.

He had an extensive criminal record, including at least 19 arrests, a two-year prison term and several stints in Georgia jails, said New York Police Chief of Detectives Robert Boyce.

Brinsley comes from a Muslim family. Relatives said he "has never expressed any radicalization," Boyce said.

Brinsley's aunt and sister told CNN affiliate WCBS that the family struggled to understand why he was set free after so many run-ins with the law.

"They kept releasing him into the streets," Jalaa'a Brinsley said, "so isn't that a problem that the justice system should be asking, not us?"

Authorities are investigating how Brinsley got the gun he used in the attack. A man purchased the handgun at a Georgia pawn shop in 1996, when Brinsley was 9.

Investigators said Brinsley's mother described her son as "very often violent," following "a very troubled childhood." He had tried to commit suicide, she told them, according to Boyce.