SPRINGFIELD, Ill. (AP) — The Chicago Police Department knew that Officer Carlos Baker was reckless and posed a threat to his partner, Krystal Rivera, before Baker fatally shot her last summer while the pair attempted to apprehend a suspect with a gun, a lawsuit filed Thursday claims.

Rivera, 36, had told supervisors she feared for her safety with Baker as her partner and had ended a two-year on-again, off-again romantic relationship with him shortly before the shooting on June 5, according to the lawsuit.

The lawsuit was filed in Cook County Circuit Court by Rivera’s mother, Yolanda Rivera. It names Baker and the city of Chicago as defendants and seeks compensatory and punitive damages of more than $50,000 for most of its nine counts. It contends Baker shot Rivera in the back and failed to notify anyone of the shooting or render even rudimentary first aid to her.

“Krystal understood the dangers of this job. She accepted the risk that came with policing. What she never should have had to fear was her own partner,” Yolanda Rivera said at a news conference. “That betrayal cost Krystal’s life.”

A spokesperson for the Chicago Police Department, which was not named as a defendant, declined to comment on the lawsuit. Baker does not have a listed phone number and it is unknown if he has an attorney. An email message seeking comment from the city was not immediately returned.

Rivera and Baker, both members of a police tactical unit, had conducted a traffic stop on a motorist suspected of having a gun. A foot chase ensued and ended outside an apartment. According to the lawsuit, Baker was positioned in front of the door and Rivera to the side or behind him. Baker kicked in the door to reveal the suspect with a gun. Baker fired his weapon but struck Rivera in the back, Rivera family attorney Antonio Romanucci said, but instead of reporting that an officer had been hit, he fled to another floor of the apartment building.

“He did not attempt even the most basic first aid step of applying pressure on her wound to mitigate blood loss, or try any other lifesaving measures,” Romanucci said. “Baker left Krystal there on the floor, literally gasping. Krystal radioed in her own shooting.”