Opening arguments are over and testimony begins in the trial of an alleged cop killer.

Demetrius Blackwell of Queens is accused of fatally shooting NYPD officer Brian Moore back in May of 2015.

35-year-old Moore was in his patrol car in Queens Village at the time.

Backwell is also accused of attempting to kill his partner Erik Jansen.

The defense is planning to call in a doctor to testify that Blackwell's epilepsy and a related surgery before the crime may have played a role in what happened that day.

They will also call into question the testimony of key witnesses and DNA Evidence.

PBA President Pat Lynch was not happy to hear this.

"And now we see him sit there and listen to his defense attorney make excuses, say 'Don't listen to the evidence, don't listen to the proof, don't listen to the DNA, it's all fiction, he's innocent,'" the union president said.

"Complete nonsense. He'll say he has epilepsy and that made him kill. That's an insult. This is a cold-hearted killer that thought he was a tough guy on the streets that pulled the trigger that took the life of a hero police officer, tried to kill another. Ran like a coward and now hides like a coward behind his attorney who makes up fiction."

Cameras weren't allowed in the courtroom today but it was packed with police officers and family members of Officer Moore.