The partner of the NYPD rookie charged with fatally shooting an unarmed black man in 2014 said in court Thursday that officer Peter Liang dialed their supervisor's phone number after the gun went off — but then he yanked the cell phone out of Liang's hand and hung up the call.

Prosecutors accused Liang, 28, of failing to render first aid and alert his supervisors after his gun discharged and a bullet ricocheted, fatally striking Akai Gurley in the chest in the stairwell of a Brooklyn housing project. Liang, who is charged with manslaughter, criminally negligent homicide, assault, reckless endangerment, and two counts of official misconduct, claims his firearm went off accidentally.

The partner, Shaun Landau has been granted immunity from prosecution.

Landau testified Thursday that after the two officers argued over who should call their sergeant — but before they realized the bullet struck Akai Gurley – Liang dialed their supervisor's number but Landau grabbed the cell phone and hung up before the call was completed.

Landau did not elaborate or explain why he hung up the call other than to say he was in shock after the gun went off.

Liang's lawyer, Robert Brown, grilled Landau about inconsistencies in his account of his partner's actions and statements after the fatal shooting in Brooklyn's Pink Houses on November 20, 2014.

There appears to be a discrepancy in Landau's testimony regarding the time that lapsed between the gun firing, the officers entering the stairwell, and the call for an ambulance.

At the trial and during a grand jury testimony in February 2015, Landau said that he and Liang waited approximately four minutes before they inspected the stairwell.

Brown said that during police interrogations the days after the shooting, Landau told investigators he and Liang waited approximately 30 seconds before entering the stairwell.

"At that moment, I was exhausted," Landau said of the 2014 police interrogation. "I was pulled out of the hospital bed to go do the interview and I was still very, very stressed out."

Then, a month later in December 2014, Brown said Landau told assistant district attorneys that they waited 60 to 80 seconds.