In early 2004, a young fugitive knocked on Bill Allen's door. Bambi Tyree, then 23 and a suspect in one of the most notorious sex and drug rings in recent Anchorage history, had been on the run from police for weeks. She came to Allen looking for help.

At the time, Allen was head of VECO Corp., the largest oilfield services contractor in Alaska, and a major Republican campaign contributor. Allen would later plead guilty to federal bribery and conspiracy charges in a corruption probe into his dealings with former state lawmakers and two of Alaska's three congressional delegates, U.S. Sen. Ted Stevens and U.S. Rep. Don Young. Allen emerged last May as a key government witness in the feds' sweeping investigation, one that stretches from Juneau to Washington, D.C., Seattle to Anchorage.

When Tyree showed up on Allen's doorstep, she was fleeing an underworld of crack addiction and sexual abuse. Allen was friends with Tyree and knew her father, said Bob Bundy, Allen's lawyer. In 2000, her father helped Allen and his company remodel and expand Stevens' Girdwood home, according to the project's foreman--an effort that is now part of the government's high-profile probe into the senator's life.

Tyree, who had a warrant out for her arrest, asked Allen if she could stay at his house, Bundy said. Allen declined, though he did not report her to police, either. The next day she turned herself in to authorities, Bundy said. Tyree, prominent businessman Josef Boehm, and two other men were federally charged, and ultimately pleaded guilty, for their roles in a conspiracy to provide crack cocaine to girls as young as 13 in return for sex.

But police were not done investigating.

Now, for the first time publicly, Anchorage police say Allen's name came up in a separate sex-crime investigation in 2004. That probe was spawned by a tip authorities received as they were still building their case against Tyree and others.

Little is known about this other investigation--including how Allen was involved. Anchorage detectives claim they suspended the case shortly after launching it. The federal government told detectives that it could have interfered with a case it was working, according to an Anchorage police spokesman. But four years later, an FBI spokesman said his agency never asked police to halt the probe. And Bundy said he and Allen know nothing about the police investigation.

(UPDATED: Sources at the U.S. Attorney's office in Anchorage confirmed after this story ran that federal prosecutors had asked police in 2004 to suspend the case because 1) they wanted to focus on the larger sex-ring investigation and 2) that the allegations against Allen were difficult to prove.)

The substance of that investigation is raising questions about Allen's cooperation with the feds' ongoing corruption probe. Last fall, Allen's testimony on behalf of the government helped win convictions against former Alaska Reps. Vic Kohring and Pete Kott for accepting his bribes. Kott and Kohring's lawyers said they are unaware of the police investigation. Had they known the case existed and might have been suspended at the request of the federal government, the lawyers said they would have pressed prosecutors to disclose details to see if it played a role in Allen's plea agreement.

"If the government has done things for Bill Allen in the past, I have the right to know about that," said lawyer John Henry Browne, who represents Kohring.

The investigation in which Allen's name surfaced in 2004 came in the wake of a sensational bust in a South Anchorage neighborhood. In December 2003, Anchorage police raided Josef Boehm's Oceanview Drive home, discovering a world of sex, drugs and underage girls. Tyree, who dated Boehm off and on for years, was deeply involved in the ring

In early 2004, as detectives and federal agents were building their case against Boehm, Tyree and their co-conspirators, police received a tip from somebody related to the investigation about another alleged crime.

This led detectives to launch a separate probe, said Lt. Paul Honeman, an Anchorage Police Department spokesman. "There was an investigation that we were beginning that Bill Allen came up in," Honeman said.