Robert Bishun, a witness in a cop case was abducted and strangled in the back of his BMW.

An NYPD cop accused of running with a violent drug crew had his bail revoked Wednesday after a cooperating witness set to testify against him was whacked “Don Corleone” gangland-style in the Bronx, the Daily News has learned.

Federal Judge Colleen McMahon made the declaration just hours after victim Robert Bishun, 36, was abducted from his auto body shop and found strangled in the back of his BMW in Fieldston late Tuesday.

“I’ve been around the racetrack once or twice. It certainly sounds like a contract killing,” McMahon said, adding that Bishun’s slaying smacked of “movie violence.”

Details of the grisly murder were outlined in her coutroom by federal prosecutors from the Southern District, who noted the mechanic had been expected to testify against disgraced NYPD Officer Merlin Alston, who’d been out on bail. Alston, 34, is facing narcotic conspiracy charges for being a helper, driver and shotgun-toting bodyguard for a drug-dealer over a four-year period.