A former employee of Affiliated Computer Services Inc. was investigated in connection with the theft of a computer containing sensitive information about thousands of Coloradans last year.

The suspect, a 33-year-old Denver man, was never charged in the case, even though he has a history of arrests for identity theft-related crimes.

"The investigation included information about a suspect but we declined to file criminal charges in the case," said Lynn Kimbrough, spokeswoman for the Denver District Attorney's office.

"We can't prove who took the laptop. There was no reasonable likelihood of conviction."

The Rocky Mountain News is not naming the man since he was never charged with the crime.

The identity of the suspect was confirmed by two law enforcement officials familiar with the investigation. The man could not be reached for comment Monday.

A desktop computer was stolen from the 27th floor of Affiliated Computer Services in the 1900 block of Broadway during the weekend of Oct. 13.

The Dallas-based company, which processes child support payments for the Colorado Department of Human Services, notified nearly 500,000 Coloradans of the loss, citing concerns about identity theft.

According to investigators, the suspected ACS employee had quit his job at the firm soon after the theft was discovered. The computer was never recovered.

A check of court records for the former employee showed that he had been arrested numerous times for theft, forgery and criminal impersonation, as well as possession of financial devices.

The man was convicted of theft in a 1994 Glendale case and was sentenced to four years probation, which was revoked in 2000. He was then sentenced to three years in prison.

It was not known Monday what, if any, kind of background check the company conducts on its employees, what his job was, and what access he had to sensitive information at ACS.

Kevin Lightfoot, spokesman for ACS, was traveling Monday and could not be reached for comment.

After the theft of the computer, the Colorado Department of Human Services withheld payment to ACS, pending an outside audit of its security protocols.

"We're still withholding payment," Liz McDonough, spokeswoman for the department, said Monday. "They are not getting paid until they submit the security audit which we required of them."

In the meantime, the company is still handling child support payments for the department.

"They're still doing the work, since they're still under the contract to provide the services," said McDonough.

Since the computer theft last October, the state's human services department has split the contract for the family support registry into four parts, with different companies bidding for them.

The department also has included provisions in the new contracts that address security.

ACS' current $5.5 million contract with the department is due to expire in June.

"We're putting in specific penalties for security breaches and requiring encryption at as many levels as possible and appropriate," McDonough said.

So far, there have not been any reports of misuse of the data in the missing computer.