Anthony Comello, suspect in fatal shooting of Gambino crime boss Frank Cali.
Cali didn't think Comello was worthy of associating with a woman in his family, the sources added.
It was the first execution of a mob boss in New York City in more than 30 years.
Cali, 53, was a high-ranking member of the Gambino organized crime family and was believed to be the acting boss, a law enforcement source confirmed.
Cali allegedly had strong ties to the Sicilian mob.
Surveillance video of the killing showed a man, allegedly Comello, crash his vehicle into Cali's parked SUV, drawing Cali outside in what might have been a ploy to lure him out of the house, Shea said. He was reportedly picked up at a New Jersey home by U.S. Marshals.
The suspect "is now being held in jail in New Jersey pending court appearances, where we anticipate we will have him returned to Staten Island to face murder charges for the death of Francesco Cali, which occurred on this past Wednesday evening", Shea said.
"The investigation is still in progress and an arrest has not yet been made", said Dermot Shea, NYPD chief of detectives, who will be hosting a press conference at One Police Plaza Press Room to discuss this case. He is listed as single and a high school graduate. Comello received a parking summons for his truck on Staten Island the day of the killing, Shea said.
Shea says Cali emerged from his home around 9:15 p.m. after the suspect backed his pickup truck into Cali's Cadillac SUV.
When this reporter retweeted Angel Gotti's post, observing that some people thought the murder suspect "may have had a screw loose", Angel Gotti responded, tweeting "A screw lose?"
As news of the arrest emerged on social media, the daughter of late Gambino godfather, John Gotti, tweeted "I can't wait to see ALL the apologies to my uncle".
Cali, a native of the Italian island Sicily, served in the organization's ruling panel for years before replacing Domenico Cefalu in 2015. He had ALL screws lost!
49 dead in New Zealand mosque shootings
When asked why they weren't on any lists, Ardern said: "It's an indication they had not acted in a way that warranted it". Australian Prime Minister Scott Morrison on Friday confirmed the attacker at the Masjid al Noor mosque was an Australian.