An arrest has been made in connection with the killing of Francesco Cali, a reputed boss of New York's Gambino crime family who was gunned down in a brazen hit this week, sources tell News 4 New York.

A Staten Island man was picked up by police in at a home in Brick, New Jersey, by the U.S. Marshals, sources familiar with the investigation said.

The sources said the murder wasn't related to the mob. One source described the man in custody as a “conspiracy theory type” of guy while a second source said he appears “a bit off.”

One theory being looked into is whether the suspect wanted to date one of the mob boss's relatives and Cali told him to back off, the sources said. 

Officials Gathering Evidence From Home of Gambino Mob Boss

One source said that police were able to track the suspect, in part, through his cell phone.

Cali, known as "Franky Boy," 53, was shot to death in front of his home on Hilltop Terrace not long after dinnertime Wednesday. The 911 caller had initially reported a man had been run over by a vehicle on purpose and that he was trapped; the caller then said he had also been shot multiple times. A suspect fled the scene in a blue pickup truck, the NYPD said.

Investigators on Thursday began retrieving video from NYPD cameras positioned on the pair of roadways that lead in and out of Todt Hill, another source told NBC 4 New York. Surveillance video from the shooting scene is grainy, the source said.

But it shows the suspect’s truck apparently deliberately hitting the vehicle — perhaps to get Cali to come out of his home. The two shake hands, the license plate from the suspect's vehicle falls off, the suspect picks up the license, hands it to Cali, then pulls a gun and shoots as Cali puts the license in his own car, according to the source. 

Chief of Detectives Dermot Shea said Thursday that 12 shots were fired, with at least six striking Cali.

Shea said Cali tried to use his car as a shield to protect himself during the shooting.

The State of the Mafia in New York City

“Mr. Cali was struck several times by gunfire. In trying to elude additional gunfire, [he] fled to the rear area of his private vehicle,” he said at a press conference.

Federal prosecutors in Brooklyn had referred to Cali in court filings in recent years as the underboss of the Gambino organization, related through marriage to the Inzerillo clan in the Sicilian Mafia.

Multiple press accounts since 2015 said Cali had ascended to the top spot in the gang, although he never faced a criminal charge saying so.

His only mob-related criminal conviction came a decade ago, when Cali pleaded guilty in an extortion conspiracy involving a failed attempt to build a NASCAR track on Staten Island. He was sentenced to 16 months in federal prison and was released in 2009.

The last Mafia boss to be shot to death in New York City was Gambino don Paul Castellano, assassinated outside a Manhattan steakhouse in 1985 at the direction of Cali's swaggering 1980s-era predecessor, John Gotti.

With his expensive double-breasted suits and overcoats and silvery swept-back hair, Gotti became known as the Dapper Don, his smiling face all over the tabloids. As prosecutors tried and failed to bring him down, he came to be called the Teflon Don. Cali kept a much lower profile than Gotti.

Gambino Crime Family Boss Killed

In 1992, Gotti was convicted in Castellano's murder and a multitude of other crimes. He was sentenced to life in prison and died of cancer in 2002.