Divers with the NYPD were spotted diving in the murky waters of Central Park on Saturday in their attempt to locate the gun used to kill UnitedHealthcare CEO Brian Thompson. The search comes as police continue to look for the unknown assailant for a fourth day.

NYPD divers were spotted in the water known as the Lake, near the parks iconic boathouse and Bethesda Fountain, the official said. Since the brazen shooting early Wednesday morning, it has been reported that police have recovered two pieces of crucial evidence that might help discover the identity of the attacker.

One piece of evidence recovered was the e-bike the killer allegedly took after shooting the 50-year-old health executive. The second piece of evidence was a backpack which reportedly contained a Tommy Hilfiger jacket, according to the officials. It was also reported that police discovered an abandoned cell phone in an alley near the murder scene, which police believe to be the shooter’s as he allegedly placed a mysterious phone call 15 minutes before the assassination.

Brian Thompson gunman made mystery call on ‘burner phone’ minutes before shooting CEO dead

FBI ups UnitedHealthcare CEO shooting reward to $50,000 if ‘information leads to arrest and conviction’

Police are hoping that the ever-growing mountain of evidence will eventually lead to an arrest. It’s not yet known who the call was placed to nor if there’s a recording of it, but former NYPD investigator Paul Mauro told Fox News that the device could still be used to trace the call and determine who was on the receiving end.

“If indeed he was on a phone call right then  his phone was live  you can dump the cell tower. You are going to need the search warrant for that, and it’s a ton of data,” Mauro said. However, if the cops can pinpoint the time of the call, they can determine the cell’s number and also the number that was called using tower data.

Former FBI investigator Bill Daly also told Fox that investigators could also determine where the burner phone was purchased, whether it was in New York City or elsewhere which would also provide more information about the assassination.

The shooting happened just outside the Hilton hotel in Midtown, Manhattan, on 54th Street near Sixth Avenue at 6:44 a.m. on Wednesday. Police were summoned to the scene where they attempted to administer first aid to Thompson who was bleeding out. Officials later rushed the man to the hospital where he was pronounced dead.

Gruesome footage of the shooting itself shows the masked, hooded gunman pulling out a pistol with a silencer, and then firing a shot into Thompson’s back. The footage shows blood spurting out of the man as he stumbles forward. A nearby witness, who is sipping his coffee, sees the commotion and flees.

Police have stated that they believe Thompson was “specifically targeted”  the murder comes shortly after a series of threats his wife, Paulette, said he had been receiving as of late related to healthcare coverage from his company. Since then, the FBI has offered a generous reward of $50,000 to anyone with information.

We are seeking the publics help in identifying the unknown suspect responsible for the homicide, the FBI said Friday in a press release. In addition, the NYPD said that they would pay tipster’s $10,000 for any information leading to the man’s arrest.

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