NEW YORK (AP) — A rookie New York Police Department officer who shot an unarmed man in a housing project stairwell is nearing a trial expected to feature testimony about the officer's panicked and shaken state in the tragedy's aftermath.

Jury selection began Wednesday in the case against Officer Peter Liang. The officer has pleaded not guilty to manslaughter, criminally negligent homicide and other charges in the slaying of Akai Gurley.

Prosecutors say that Liang killed an innocent man who never posed a threat and that he argued with his partner for at least four minutes about how to respond before the victim received any medical attention.

During the exchange, Liang said, "I'm going to be fired," according to the partner, a key prosecution witness.

The shooting occurred in November 2014 while the 28-year-old Gurley was visiting the Louis Pink Houses, a public housing complex in Brooklyn. Liang, who had been an officer for about 18 months, and the partner were patrolling the complex where reports of violent crime had spiked.

Liang had his gun drawn as they descended onto an eighth-floor landing in a darkened stairwell, prosecutors said. Meanwhile, Gurley opened the door into the seventh-floor landing after giving up his wait for an elevator. Liang, gun in his left hand and a flashlight in his right, fired a shot, prosecutors said. The bullet ricocheted and struck Gurley in the chest, who made it down two flights of stairs before collapsing.

Defense attorneys have indicated that Liang will take the witness stand to tell jurors he didn't mean to fire his weapon. At a pretrial hearing, a police lieutenant who's also expected to testify, quoted Liang as telling him, "I shot him by accident," and described the officer as "unsteady on his feet and incoherent."

The investigation of the shooting was closely watched in New York City following the December 2014 decision not to indict a police officer in the chokehold death of Eric Garner. That decision — along with the another grand jury's refusal to charge an officer in the shooting of Michael Brown in Ferguson, Missouri — prompted mass protests decrying the grand jury system as biased.