Forensic tests have confirmed the gun divers discovered in the East River Sunday is the weapon used to kill NYPD officer Randolph Holder, who was shot in the head as he responded to a call of shots fired with his partner near the FDR Drive last week, authorities said Monday.

Witnesses had said the suspect who allegedly killed Holder tossed something into the river after Tuesday's shooting and divers scoured the river at strategic intervals for days in search of it. They recovered the weapon at 3 a.m. Sunday, Bill Aubry, chief of Manhattan detectives, said.

The .40-caliber Glock pistol, which was found 20 feet under water, was being tested for fingerprints and DNA. Shell cases from the test firing were to be compared with discharged cases police recovered on 120th Street next to Holder's body -- in addition to the cases at 102nd Street where the first shots were fired, Aubry said.

Authorities said Monday the gun has been definitively matched to both investigations, though further testing will be conducted. 

Holder and his partner had responded to a report of shots fired near a public housing development in East Harlem on Tuesday night. When they arrived, a man said his bike had been stolen at gunpoint and the thief fled.

The officers caught up to a man with a bike on a pedestrian overpass that spans FDR Drive and traded gunfire, police said. After Holder was shot, the gunman ditched the bike and took off, apparently throwing his weapon into the river, police said. He was caught several blocks away with a gunshot wound to his leg, NYPD Commissioner Bill Bratton said.

Tyrone Howard, 30, has been charged with murder and robbery in Holder's death. His lawyer has said there are many missing details in the case.

Holder's funeral is scheduled for Wednesday. He is to be buried in his native Guyana.