SEATTLE -- An investigation by the King County Sheriff's Office has revealed troubling details about security guards working for Metro Transit.

The investigation uncovered the criminal records of eight security guards, two of whom had outstanding warrants.

Sheriff's detectives made their first discovery during a routine check. They realized a security guard assigned to Metro Transit's downtown tunnel had a warrant for a drug charge.

After that guard was fired and arrested, detectives opened the books. That's when they found another guard with a warrant for domestic violence. They also found six more guards with misdemeanor convictions, which make them ineligible to work.

Detectives blame the law for the oversight.

"It's not surprising because of the way the law is constructed," said Sgt. Jim Laing.

According to the state law, anyone applying for a license to be a security guard must be subjected to a background check. However, new employees can still work under a 60-day permit while their screening is completed. In other words, Laing says, criminals can be patrolling for criminals without anyone knowing.

"That flaw needs to be remedied by the state; we have no control over it," he said. "But proactively we're now jumping ahead and front-loading these people so we're doing background investigations before they go into the tunnel."

Olympic Security Services in Tukwila hired all eight guards and did not returned phone calls seeking comment.

But the company's president told our newspaper partner, the Seattle Post-Intelligencer, they would be taking appropriate action, saying "if someone is not acceptable for the job, we make a change especially if they're breaking the law."

But Seattle police say that may not be enough. The job of patrolling the tunnel used to fall on off-duty officers, but a cost-cutting move changed that. The city's police union says as long as security workers are present instead of police officers, citizens should expect more trouble ahead.

Read the full report in Thursday's edition of the Seattle P-I.