Two decades ago, a fast-talking former bill collector from Chicago blew into Los Angeles to help unravel the U.S. government's drug case against carmaker John DeLorean.

Part salesman, part sleuth, Anthony J. Pellicano quickly made a name for himself as the kind of bare-knuckles fighter that celebrities and entertainment moguls wanted in their corner. Someone who could make problems — including lawsuits — go away.

At the same time, Pellicano was forging relationships with law enforcement officers that helped back up his reputation as Hollywood's ultimate fixer.

"These relationships were vital to Anthony," said a former associate, who requested anonymity because of the ongoing FBI investigation. "As a P.I., you can only go so far getting information. And he had cop friends everywhere."

Detectives. Prosecutors. Federal agents. He helped them. And as a still-unfolding FBI investigation suggests, some returned the favor by providing him with the kind of information that only someone in law enforcement can access.

This week, a federal indictment charged Pellicano and former LAPD Sgt. Mark Arneson with running a vast racketeering enterprise that wiretapped, blackmailed and intimidated the private eye's investigative targets.

Pellicano pleaded not guilty and Arneson will enter his plea Monday. Their attorneys could not be reached for comment.

The indictment followed a guilty plea last month by veteran Beverly Hills Police Officer Craig Stevens to charges of illegally accessing government computers to dig up dirt for Pellicano.

Both police departments describe the charges as aberrations. But sources close to the investigation say other law enforcement officials have come under scrutiny. And the former Pellicano associate told The Times how he regularly had contact with about a dozen law enforcement officers throughout the region.

Pellicano's legitimate ties to law enforcement may have emboldened him to think he was "cloaked in some sort of quasi-judicial role with law enforcement," said veteran Los Angeles defense attorney Mark Werksman, who has tried a number of high-profile cases.

And those connections, Werksman said, could not help but be used by Pellicano to drum up new clients. "I have no doubt that he would sell his services by promoting his special relationship with the government," said the former federal prosecutor.

An audio forensics expert, Pellicano's specialty was enhancing or authenticating garbled or faint tapes.

Dozens of times, authorities across the country turned to Pellicano to apply his expertise to problem cases. In an especially high-profile prosecution, Pellicano testified against Thomas Blanton Jr., a former Ku Klux Klansman accused in a 1963 church bombing in Alabama that killed four African American girls.

Pellicano was able to enhance nearly 40-year-old tape recordings on which Blanton can be heard telling his wife about a meeting to plan the bombing of Birmingham's 16th Street Baptist Church, bolstering the government's case. Blanton was convicted in 2001 of murder and sentenced to life in prison.

"Through your tireless efforts we were able to produce to the jury an audible recording of a critical conversation in which the defendant clearly admitted his involvement in this horrible crime," G. Douglas Jones, the prosecuting U.S. attorney, wrote Pellicano after the trial.

The letter, one of many written on Pellicano's behalf over the years by law enforcement officials, could only bolster his reputation. And as time passed, he found more work as both a government witness and a high-priced private eye.

"He tried to play both sides against the middle," Werksman said. "He would allegedly try to obtain things clients were not entitled to get. And on the other hand, he had the government hiring him because of his professed ability to analyze audiotapes as a result of his years of dealing with electronic surveillance."

Of all the relationships with law enforcement officers that have so far surfaced, none seems to have been tighter than his alleged connections with Arneson, the former Los Angeles Police Department detective.

A decorated 29-year veteran who spent a large part of his career as a homicide detective in South Los Angeles, Arneson could be seen in Pellicano's offices as often as three times a week, according to the former Pellicano associate.