According to current and former Newark police officials, the police director's account had traditionally been primarily used to pay for confidential informers in drug investigations.

He said permission from a judge for the electronic surveillance was based on evidence from confidential informers who feared being identified.

The investigation also resulted in the police taking steps to improve their procedures on search warrants and the use of confidential informers.

Frank Prewitt's identity as the confidential informer was later confirmed.

In recent years, he said, the Police Department has vastly increased its roster of confidential informers.

Those warrants were based largely, or solely, on the word of confidential informers.

Mr. Archie also raised questions about the confidential informer, who prosecutors said was central to the case.

The inquiry began when investigators in North Carolina received a tip from a confidential informer, officials said.

Chief Campisi said investigators had begun looking into the officers two years ago after getting a tip from a confidential informer.

But at a court hearing today the prosecutor in the case repeated the allegation and said it was based on information from confidential informers.