TODT HILL, Staten Island (WABC) -- Details continue to emerge as the investigation advances in the murder of a reputed Gambino family mob boss outside his Staten Island home, the first such incident in New York in three decades.Multiple police sources say that whoever shot Francesco "Frankie Boy" Cali drove up to the mobster's Hilltop Terrace home in the Todt Hill section, came to a stop, and then gunned the engine in reverse, crashing into Cali's parked Cadillac SUV.The force of the impact knocked the license plate off the SUV and seemed to investigators to have been done intentionally in order to get Cali's attention.Once Cali came outside the home, sources said, video showed the two men talking and then shaking hands. Apparently Cali sensed no danger, because he turned his back on his killer to put the license plate inside the rear of the SUV.That's when the gunman took out a 9mm handgun, held it with two hands -- as if he was trained, the sources said -- and opened fire.The video is said to be grainy and has not been released because the suspect's face cannot be seen. The NYPD is continuing to canvass the neighborhood in search of clearer video.Cali's wife and child were in the home at the time, which sources say is a highly unusual circumstance in the lore of organized crime -- which, in its heyday, followed certain rules that kept targets from getting whacked in front of their families.Eyewitness News obtained Cali's mugshot from 2008, when he pleaded guilty in an extortion scheme involving a failed attempt to build a NASCAR track on Staten Island. He was sentenced to 16 months behind bars and was released in 2009. It is believed he took the reins of the notorious Gambino crime family in 2015.Mob experts have been wary about possible conflicts erupting in the crime family, particularly after the brother of former Gambino boss John Gotti recently was released from prison. Gene Gotti is a reputed captain.They say the type of hit -- at his home, with no real attempt to hide what happened -- suggests that it was a message killing. The question for detectives is what type of message was being sent.This is the first time a reputed mob boss has been killed in New York City in more than 30 years.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 Gotti, who then took over.Cali kept a much lower profile than 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.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.----------