Slain Gambino crime boss Francesco “Franky Boy” Cali shook hands with his killer before he was gunned down in a fusillade of bullets, a high-ranking police source told The Post Friday.

The interaction was captured on surveillance footage from Cali’s brick mansion in the Todt Hill section of Staten Island.

Cali, 53, exited his home shortly before 9:20 p.m. Wednesday after a motorist in a blue pickup truck reversed the vehicle into the mobster’s parked Cadillac Escalade, causing it to “rock significantly,” Chief of Detectives Dermot Shea has said.

Footage from the property, which authorities obtained using a search warrant, shows Cali and the man having a conversation and shaking hands before the man passes Cali the license plate that fell off the Cadillac during the crash that lured the Gambino don outside, sources said.

The hit man — approximately 25 to 40 years of age — opened fire with a 9 mm weapon as Cali turned his back and was putting the license plate in the trunk of the Escalade, according to sources.

“It’s not like they came out, started a fistfight,” the high-ranking source said. “The importance of that is — it’s almost as if proof of the concept that hitting the car was contrived.”

“It doesn’t look like there was any rage,” said the source.

The gunman fired 12 rounds, shooting Cali at least six times.

“I heard five shots. Two at first and then three more. I was frightened,” said a longtime neighbor, Rose Zaccaria, 90. “That night it looked like a murder mystery. A lot of vehicles and lights and commotion. Like a scene from the movies.”

Cali tried to escape the hail of bullets by hiding under the Cadillac, which initially led investigators to believe that he had been run over during the attack. Police no longer believe that was the case.

The city Medical Examiner’s Office ruled Friday that Cali died from gunshot wounds, an ME source said.

Cali’s body was transferred from the Kings County Hospital morgue on Friday to the Scarpaci Funeral Home on Staten Island where a wake will be held for him, sources said.

Meanwhile, officers armed with a search warrant removed electronics, including cellphones and laptops, from Cali’s home Thursday as police deepen their investigation into the slaying, sources said.

Authorities continue to eye 72-year-old Gene Gotti, a brother of the late Gambino crime boss “Dapper Don” John Gotti, in the killing, according to law enforcement sources who say the hit on Cali was not sanctioned by New York’s five Mafia families.

Gene Gotti was released from prison in September 2018 after spending 29 years behind bars for heroin dealing.

“Everything was running smoothly. Everybody was making money and something like this is only bad for business,” a law enforcement source said. “Now they’re back on the front page.”

Additional reporting by Nick ­Fugallo