Murder trial begins in killing of NYPD Detective Brian Moore in Queens

QUEENS VILLAGE, Queens (WABC) -- The murder trial of a Queens man accused of gunning down a New York City police detective in May 2015 got underway Friday.

It was nearly two and a half years ago that then-Officer Brian Moore was brutally murdered, and opening arguments began in the trial of 37-year-old Demetrius Blackwell, who has pleaded not guilty to aggravated murder and other charges.

The brotherhood of the NYPD was on full display, as dozens of officers packed the courthouse.

Moore was just 25 years old, but he was already a decorated NYPD officer with more than 150 arrests.

He and his partner, Officer Erik Jansen, 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.

Prosecutors said in court that they have three eyewitnesses, including Jansen, and they also revealed Blackwell cried in the squad car after his arrest and had both cocaine and marijuana on him that was later discovered at the precinct.

They said that fleeing the scene, Blackwell stopped at a nearby house, where he changed into stolen clothes and left behind a gun with DNA evidence.

Meantime, defense attorneys are blaming Blackwell's mental health, saying he suffers from epilepsy and had a brain surgery two years prior that left him with cognitive troubles. That defense, though, has done little to soothe the department's sense of loss

Moore was posthumously promoted to Detective First-Grade.

Blackwell faces up to life in prison without parole if convicted.

(The Associated Press contributed to this report.)