CHICAGO, United States (AFP) – A Chicago police officer plans to sue the family of a black teenager he shot and killed, claiming emotional distress, US media reported Friday.

The teen’s neighbour — a mother of five — was caught in the crossfire after answering the door and was also killed by police in the December 26 incident.

The shooting came as the US city was reeling from a series of incidents in which police were accused of being too ready to pull the trigger on their service weapons.

City officials apologised for the death of Bettie Davis, 55, but have said Quintonio LeGrier’s shooting was justified.

The family of LeGrier, 19, has repeatedly said there was no reason why police should have opened fire when responding to a domestic disturbance at their home.

Police said LeGrier was brandishing a baseball bat and threatened the responding officer.

His family insists there was no need to respond to the mentally disturbed teen with deadly force when all they were doing was asking for help.

Officer Robert Rialmo plans to file a civil suit against LeGrier’s estate, citing emotional distress and assault, his lawyer Joe Brodsky told WGN-TV.

Brodsky did not immediately return a request for comment.

Police tactics and racism have been the subject of a national debate since protests erupted in Ferguson, Missouri, in mid-2014 over the shooting death of a black teenager, 18-year-old Michael Brown.

The US Justice Department is investigating how Chicago police use force after the death of another black teenager, Laquan McDonald, who was shot 16 times as he was walking away from officers.