NEW YORK (AP) — The murder trial of a Queens man accused of gunning down a New York City police officer in 2015 is set to begin.

Thirty-seven-year-old Demetrius Blackwell has pleaded not guilty to aggravated murder and other charges in the death of Police Officer Brian Moore. Opening arguments are scheduled for Friday.

The 25-year-old officer and his partner were in street clothes in an unmarked car when they attempted to stop Blackwell, who was suspected of carrying a handgun. Authorities say Blackwell opened fire, striking Moore in the head. He died two days later.

Moore was posthumously promoted to Detective First-Grade.

If convicted, Blackwell faces up to life in prison without parole.