This is a classic case of what we call purchased testimony. Testimony bought with promises of leniency. Here's the story:

A federal judge in New York has overturned a murder conviction in a Brooklyn gang case because prosecutors relied on "blatant, critical perjury by all of the key witnesses."

The judge, John Gleeson, stopped short of saying the federal prosecutors in Brooklyn knew that their witnesses were lying at a jury trial in April. But in an extraordinary 60-page decision, the judge was clearly distressed by the actions of the prosecutors from the office of the United States attorney, Roslynn R. Mauskopf. Judge Gleeson said he feared that an innocent man had been convicted on "patently incredible testimony" and had a "concern that perjury was deliberately elicited'' by the prosecutors.

The decision was a raw judicial exploration of familiar claims by defense lawyers that prosecutors rely excessively on witnesses who get lenient plea deals and lie.

After the judge's ruling, prosecutors made a deal with Angel M. DeAngelo, the once-convicted killer: They dropped the murder in aid of racketeering charge and allowed him to plead guilty to making a false statement --denying he had been present at the murder. He's already been released:

"How many other people did they do this to?'' Mr. DeAngelo asked yesterday in a telephone interview from Latham, N.Y., near where he now lives. "They believe anything these people say. It's all about a collar; it has nothing to do with justice.''