NYPD Officer Peter Liang was a nervous wreck moments after fatally shooting an unarmed man in a Pink Houses stairwell, his supervisor testified Tuesday. View Full Caption Pool/Jesse Ward

BROOKLYN SUPREME COURT — The NYPD officer who fatally shot an unarmed dad in the stairwell of an East New York housing complex 14 months ago was a nervous wreck after the incident, his supervisor testified Tuesday — which his defense attorneys claim is why he didn’t render aid as the victim lay dying.

Officer Peter Liang, who is awaiting trial for criminally negligent homicide and official misconduct, was having trouble breathing after fatally shooting Akai Gurley, 28, in a dimly-lit Pink Houses stairwell Nov. 20, 2014, his supervisor and defense attorney said.

“He appeared pale, he was incoherent when he was talking,” NYPD Lieutenant Vitaliy Zelikov testified in Brooklyn Supreme Court Tuesday, as part of a pre-trial hearing. “He was unsteady on his feet. He appeared to have difficulty breathing.”

Liang didn't lift a finger for four minutes as Gurley bled to death, prosecutors have said.

But Defense Attorney Robert Brown claimed that Zelikov’s testimony showed Liang was in no shape to assist.

“It’s going to be pretty clear he broke down and was crying in the hallway, not necessarily the best physical and mental condition to perform CPR on someone,” Brown said.

Zelikov said when he first encountered Liang on the fourth floor, he asked if anyone had been shot, and Liang pointed to the fifth floor.

“He said, ‘I shot him by accident,’ Zelikov said.

Zelikov added that he then removed Liang’s gun, per protocol, before walking up a flight of stairs.

“I saw an individual who appeared to be shot laying down in the stairwell,” he said. “There was a female there trying to render aid. She was doing chest compressions and mouth-to-mouth.”

Zelikov said he then instructed another officer to perform first aid.

Liang is expected to testify when the jury trial gets underway.

“We anticipate that he will,” Brown said. “I think he wants to tell his side of the story.”

Jury selection is expected to begin Wednesday afternoon.