He started serving his sentence in October 2004 and his earliest projected release date was more than 16 years from now, on June 29, 2029.
It is not the first time a prisoner has been mistakenly freed from the Cook County Jail.
In 2009, Jonathan Cooper, who was serving a 30-year manslaughter sentence in Mississippi, was brought to Chicago to face charges that he failed to register as a sex offender.
Prosecutors dropped the charges because, as an inmate, he could not comply with the Sex Offender Registration Act.
A clerk reportedly failed to include the Mississippi sentence information in Cooper's file, and jail staff released him.
Cooper turned himself in several days later.
In a more recent embarrassment for law enforcement officials in Chicago, two convicted bank robbers escaped from a high-rise federal lockup in December by climbing down the side of the building on a rope made of bed sheets and jumping into a cab. Authorities recaptured both men, one of whom remained on the run for about two weeks. Officials have yet to provide a public explanation of the jailbreak.