BIDDEFORD, Maine (AP) — The parents of a Biddeford man who was shot and killed minutes after police had left his apartment building plan to sue the city and police department.

Police say 19-year-old Derrick Thompson and his 18-year-old girlfriend, Alivia Welch, were shot and killed on Dec. 29 by their landlord after he argued with them about late rent, snow shoveling and parking.

Thompson's parents say they intend to file a lawsuit seeking at least $1.5 million in damages.

Police had come to the apartment after Thompson had complained that 75-year-old James Pak had been yelling at him and threatening him. An affidavit says the two officers determined the argument had been about late rent and parking, which they deemed a civil matter and left.

Pak has pleaded not guilty to two counts of murder.