NASHVILLE, Tenn. -- The city of Nashville has put a security contractor on notice in its investigation of the Davidson County Election Commission's stolen laptops.

Video: Commission Security Contractor Put On Notice By Metro

The move comes after some accusations that were levied against the company in charge of security where the laptops with voter information were stolen.

Since last week, the Channel 4 I-Team has been investigating allegations that guards were routinely not on duty at the office when they were supposed to be.

For the first time, Metro officials admit what Channel 4 learned is true.

The Channel 4 I-Team first brought the issue to the city's attention last week when it started pulling billing records. That was after Channel 4 was told by former security employees that Metro had been billed for hours that were not really worked by security guards -- exactly what a preliminary audit by Metro officials showed on Tuesday.

City officials who looked at the documents said "there were many instances" where Wackenhut billed Metro for services that were not performed.

"So, we've discovered some discrepancies, potentially, in the Wackenhut, in terms of their billing versus actual people around,” said Finance Director Rich Reibling.

According to the I-Team’s Nancy Amons, the audit went on until the early morning hours at the city's General Services Department. Amons said the findings, as she was told by sources, were relayed to Mayor Karl Dean Tuesday morning.

Channel 4 previously asked Mayor Karl Dean in a one-on-one interview on Monday about the allegations.

“I am not privy to the information you have. It's not been presented to us in any form or fashion at this point at all, but if there (are) ghost employees, if we are being billed for something from a contract that's existed for some time, then we are going to get to the bottom of it and we're going to take appropriate action,” he said.

In a letter to security contractor Wackenhut on Tuesday, Metro put the company on notice that there will be a full audit of all billings and that it may no longer use its subcontractor, Specialized Security Services, which is located in Wilson County.

The General Services Division said Metro was billed for 12-hour Saturday shifts from October to December but it questioned whether anyone was really there and said they can track someone’s presence in the building by seeing who used an access card to get in.

The former guard and three other people who used to work for Wackenhut or its subcontractors told the I-Team that Wackenhut billed Metro for hours when no one was really working.

"I felt that Wackenhut Corporation was committing a felony by charging a government contractor something that wasn't used,” the former worker said.

Last week, the I-Team asked Wackenhut about the employees’ allegations, and its corporate spokesman dismissed them and said, “The information you have been given alleging ghost workers is absolutely false. There were no deliberate acts of over billing made by the company."

The employee who made the allegations to Channel 4 said Wackenhut's corporate office should have known because he wrote them two letters - one last year and one this year - detailing billing irregularities in the Metro contract.

“I think they ought to go through and audit the whole thing,” the former worker said.

Metro hired an independent accounting firm to go through all the records.

Late on Tuesday, Dean said he's disappointed.

Wackenhut is also under federal investigation in Florida because of questions raised by a TV station in Miami.