The desktop computer, which was stolen during the weekend of Oct. 13, had data on clients who were involved with child support payments. It was stored in a secure area monitored by surveillance cameras accessible only by password, said Dallas-based Affiliated Computer Services Inc.
Company spokesman Kevin Lightfoot said letters were sent to the clients about the theft and advised on how to protect their information.
There was no evidence of identity theft or an intent to do so, he said.
Department spokeswoman Liz McDonough did not say how many clients could be affected and where the theft occurred, citing the cases involves child support.
Detectives were investigating the theft and were trying to recover video from the surveillance cameras, said Denver police spokesman Sonny Jackson. Colorado Bureau of Investigation and officials from the human services department were assisting detectives.
"We are monitoring the actions of the contractor to make sure they meet the expectations of the state," McDonough said.