Officer Peter Liang is escorted out of court in Brooklyn after being charged with manslaughter, official misconduct and other offenses on Feb. 11, 2015. View Full Caption Spencer Platt/Getty Images

BROOKLYN SUPREME COURT — NYPD Officer Shaun Landau and his partner Peter Liang bickered about who should call their superiors for four minutes after shooting unarmed Brooklyn man Akai Gurley in a stairwell, Landau testified in court on Tuesday.

Landau spent an hour and a half on the stand answering questions about what happened in the stairs of an East New York housing project building on Nov. 20, 2014.

Liang is facing charges of criminally negligent homicide and misconduct for killing Gurley after, as he said, his drawn service weapon accidentally fired during a routine patrol.

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Landau demonstrated to prosecutors how his partner had entered the “pitch black” stairwell from the hallway on the eighth floor of the Pink Houses. “I heard a shot go off,” Landau told the court.

As his partner retreated back into the hallway, Landau told prosecutors he said, “‘What the f--k happened?’" He said Liang responded, “It went off by accident."

Then Landau said he heard someone running, but instead of pursuing the matter, the partners argued for about four minutes about who should radio dispatch as well as call their superior officer about the discharged weapon.

“[Liang] thought he was going to be fired. I said no you're not, it's just an accidental discharge,” Landau said. “I told him to call, and he told me to call. He says you call. I said you call.”

Meanwhile, Gurley’s girlfriend, Melissa Butler, testified in court earlier in the day Tuesday that she attempted to give her boyfriend CPR on the stairwell landing below.

Landau said that after the argument with Liang he went back into the stairwell to try to find the bullet hole in the wall. Instead he heard the injured Gurley. It's unclear when Landau knew that someone had been shot.

“I heard some kinda noise coming down from the fourth floor,” Landau said. “It sounded like a person. It sounded like grunting, grunting, crying.”

Landau and Liang ran down the stairs to find Butler crying over Gurley’s bloody body.

Landau testified that this was when Liang radioed the incident in. However, Liang only reported their post, “Pink House One” and did not specify what had happened.

In his cross examination, Liang’s defense attorney, Robert Brown, called Landau's account into question. He noted that Landau had previously told NYPD investigators that Liang gave a more detailed account of what happened on the radio, including that there was an accidental discharge, a male was shot and that an ambulance was needed.

This discrepancy will be cleared up in court on Thursday when the records of the radio calls are presented, a source in the Brooklyn DA's office told DNAinfo New York.

Landau will not face criminal charges for his involvement in Gurley's shooting. However, he is on desk duty pending administrative charges. He also faces a civil suit from Gurley’s family.

Liang’s defense team will continue to question Landau when the trial resumes on Thursday.