Illinois' auditor has found that the state's prison systems have lost 240 computers.
Auditor General Bill Holland's report shows the Department of Corrections is missing 156 computers and the Department of Juvenile Justice can't locate 84 others.
Holland called the losses problematic because it increases the risk of exposing confidential information.
However, Corrections spokesman Tom Shaer says it's likely the computers were properly disposed of.
He says DOC believes a "human error" is at fault, such as someone not filling out proper paperwork to document the computers' whereabouts.
"It's not speculation and it's not something we hope. That's where the information is leading us to at this point. Information that we're acquiring as we go through the inventory process with Central Management Services, which was one of the main recommendations by the Auditor General."
In June the auditor found more than 250 computers unaccounted for at Southern Illinois University.
State officials estimate the value of the missing SIU and prison computers at $639,000.