The New York City police officer who shot an unarmed man in a dark public housing stairwell says what happened was a deadly accident. Prosecutors call it manslaughter and say he acted recklessly and then did little to help the dying man.

Jurors are expected to evaluate Officer Peter Liang’s actions as soon as Tuesday. Closing arguments are expected to be delivered this morning and deliberations will most likely begin in the afternoon.

The 28-year-old rookie police officer says he didn’t know anyone was in the pitch-black stairway when he unintentionally fired. The single shot ricocheted off a wall, striking Akai Gurley, 28, who was walking down the stairs.

Liang testified Monday that he was on a routine patrol in a dark stairwell with his gun drawn, his finger on the weapon’s side, when a noise startled him.

“I just turned, and the gun went off,” Liang said, explaining that his body “tensed up.”

Saying he beamed his flashlight and saw no one after firing, Liang acknowledged that he didn’t immediately report the shot. Fearing for his job, he bickered with his partner about which one would phone their sergeant.

Then he went looking for the bullet and heard someone crying. He followed the sound down three flights and saw Gurley lying wounded.

“I said, ‘Oh, my God, someone’s hit!” Liang recalled, fighting tears and turning away from the court audience. He took a brief break from the witness stand to compose himself.

As he radioed for an ambulance, Gurley’s girlfriend, Melissa Butler, tried to resuscitate Gurley, following instructions relayed by a neighbor who was talking to a 911 operator.

Yet Liang did not try to help. He said he thought it better to wait for professional aid.

Prosecutors questioned that decision and sought to show that he had been trained in handling firearms and unexpected, risky situations. Outside court, Gurley’s relatives called for Liang to be held accountable for what they see as a callous killing.

“Peter Liang walked away and left Akai to die in his own blood,” said Gurley’s mother, Sylvia Palmer.

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