A former NYPD detective accused with his partner of stealing hundreds of thousands of dollars from drug dealers is expected to plead guilty Friday. The widening federal probe of police corruption has already netted a drug bagman who worked with cops Julio Vasquez and his partner, Thomas Rachko.

That suspect, Christian Hernandez, pleaded guilty yesterday and is cooperating with prosecutors.

Vasquez's anticipated guilty plea leaves his former partner and fellow detective Rachko with few options, a source said.

"[Rachko's] really screwed," said the source.

Rachko's lawyer and Assistant U.S. Attorney Steve Breslow declined to comment. Vasquez will likely get prison time, but it will be significantly less than the 30 years the feds are offering Rachko for a guilty plea.

Authorities don't believe Rachko, who faces life if convicted of charges that include money laundering, drug conspiracy and lying to federal agents, gambled away all of his loot, as he claims, according to a source.

At least nine current and former members of the same NYPD drug task force, including two lieutenants, are under investigation for ripping off dope and cash in the department's worst corruption scandal since 30 cops went down in Harlem's 30th Precinct a decade ago.

Vasquez and Rachko allegedly used street informants, including Hernandez, to get information about drug spots they could rip off, sources said.

In Brooklyn Federal Court yesterday, Hernandez admitted that between January 2000 and last November, he and others picked up drugs in Brooklyn, distributed them in Manhattan and brought the drug cash back to Queens.

Hernandez was caught in November, when a federal surveillance team spotted him carrying $169,000 in cash through Queens. As federal agents watched, Vasquez and Rachko allegedly stopped Hernandez and took his money.

Outside court, Hernandez's lawyer, Dawn Florio, told reporters, "I don't want to comment on whether my client is cooperating or not."

A federal indictment alleges Vasquez and Rachko were distributing drugs and laundering cash since 1998. Vasquez, who retired after his arrest in November, led the feds to his $744,370 stash in a rented locker. But only $68,680 of the $169,000 taken from Hernandez was recovered, with Rachko insisting he gambled away his share of the dough.