A suspect is in custody in connection to this week’s slaying of reputed Gambino mob boss Francesco “Franky Boy” Cali outside his Staten Island home, police sources told The Post Saturday.

The suspect, who the sources say is a 24-year-old Staten Island resident, is being questioned in connection to the Wednesday night shooting

Authorities got the suspect’s fingerprint off the license plate of Cali’s silver Cadillac Escalade SUV — which he handed to the mobster after allegedly smashing into the car, the sources said.

Cali, 53, was shot several times in front of his brick mansion in the lavish Todt Hill neighborhood at about 9:20 p.m. His wife and young children were inside, police sources told The Post.

He shook hands with the shooter before he was killed, a source said.