A graduate of Columbia University, Maguire recently testified at a closed-door departmental trial where he admitted he and other rogue cops stole money on the job, the sources said. He said he used the ill-gotten gains to purchase real estate and cars.

Maguire is the fourth member of the drug unit to plead guilty to corruption charges. Three detectives previously admitted to stealing gobs of cash from drug dealers.

Sources said Maguire already was retired when he was implicated in the scandal last year.

He agreed to cooperate and was outfitted with a wire, then sent to the home of a veteran cop he claimed had stolen money with him 11 years earlier.

The officer was immediately suspicious because he had read in the newspaper that Maguire was under investigation.

"Maguire shows up out of the blue and starts asking him, 'How are things, and remember the money we stole?'" said one source.

The cop was brought up on departmental charges, and Maguire testified they had stolen $100 from the upper West Side apartment of a person who had died.

BUT ON cross-examination, when Maguire was asked about his own wrongdoing, he invoked his Fifth Amendment right against self-incrimination more than 40 times, according to Patrolmen's Benevolent Association lawyer Stephen Worth.

"It's regrettable that the department would attempt to prosecute a productive cop using a dirty cop who wants to hide behind the Fifth Amendment," Worth told The News.

An administrative judge found the cop not guilty.

The scandal came to light in November 2003 after Detective Julio Vasquez and his retired partner Thomas Rachko were caught ripping off a drug courier in Queens as members of a federal-NYPD money laundering task force videotaped the encounter.

Vasquez and Rachko were former partners in the Northern Manhattan Initiative, and they later implicated other corrupt members of the unit, including Maguire.