Detective Julio Vasquez and retired cop Thomas Rachko pulled off the theft last Wednesday morning, clad in NYPD raid jackets, authorities said.

They did not know they were being watched by other cops.

They grabbed the courier on a Jackson Heights street, handcuffed him and put him in an NYPD car. Before driving away, Vasquez looked inside the man's black shoulder bag, smiled and gave a thumbs-up to his accomplice, according to court papers.

Cops from the organized crime investigation division, which was running a major money laundering probe involving a Colombian drug ring, were waiting for the courier to drop off the bag to a man who was to ship the cash to Colombia. Instead, they saw Vasquez and Rachko grab the courier.

Crime division cops asked what was going on. Vasquez allegedly replied, "Papi, I'm on a wire," referring to a wiretap investigation, according to the complaint. The division contacted metropolitan-area law enforcement agencies and found Vasquez wasn't involved in such an investigation. They traced the license plate of his silver Toyota Avalon and found it was leased by the NYPD for Vasquez.

Vasquez, 43, an 18-year member of the NYPD and a second-grade detective, was arrested on Thanksgiving Day at his Brooklyn home and arraigned Friday on charges of grand larceny, money laundering, obstructing governmental administration, official misconduct and coercion, according to court papers.

He has been in the firearms investigation unit for about two years, and is assigned to Manhattan. The squad has been lauded by Police Commissioner Raymond Kelly for getting scores of guns off the street.

Rachko, 45, of the Bronx, retired from the NYPD last year.

Members of the firearms unit were stunned by the arrests. "It's hard to say what happened. We're all perplexed as to what went down," said an investigator. "None of us want to believe it happened."

Rachko and Vasquez were released on $50,000 bail each.

NYPD Deputy Commissioner Michael O'Looney declined comment on the arrests, but noted the probe was continuing.

Sources said the long-term money laundering probe, being conducted by the federal-state-city El Dorado task force, might have to be abandoned.