It concludes, "Good career potential."

Officer Dowd, who is 32, was finally arrested in 1992, not by New York City Police investigators, but by officers from Suffolk County. They had intercepted telephone conversations between the officer and a small-time drug dealer. He is now in the Manhattan Correctional Center awaiting sentencing on drug charges. The revelations that grew out of Officer Dowd's arrest led Mayor David N. Dinkins to announce the creation of the Mollen Commission on June 25, 1992.

The panel's report concluded that for nearly a decade the Police Department had abandoned its responsibility to insure the honesty of its members.

Fearing that reports of corruption in their commands would damage their careers, senior officers looked the other way, the commission said. Information in internal investigations was deliberately fragmented, rather than woven together to form a pattern, and cases were closed well before all leads had been exhausted.

In the fall of 1992, a report issued by Police Commissioner Lee P. Brown blamed the department's failure to intervene in the crimes of Mr. Dowd and his fellow rogue cops on a breakdown in procedures.

But the Mollen Commission said it concluded that the problem was "a willful effort" by commanders of the Internal Affairs Division, the principal anti-corruption unit, to impede the investigation. Internal Affairs, it said, treated allegations against Mr. Dowd as separate incidents and withheld critical information from another investigator.

"By doing so," the commission said, "Internal Affairs commanders doomed any hope of a successful investigation of Dowd and other corrupt officers of the 75th Precinct." Holdup Provides Example

One example of how police investigators failed to make the most of leads was the holdup on July 1, 1988, by three officers in the 75th Precinct of a grocery store that was serving as a front for drug dealing. Officer Walter Yurkiw and two others were charged with the crime after robbery investigators found the car they had used, with money and drugs visible inside, parked near the station house.