DuPage County State's Attorney Robert Berlin has been investigating whether they could keep Thomas Kokoraleis locked up, but on Friday Berlin said his office could not prove that Kokoraleis would likely commit acts of sexual violence as is required by the state's Sexually Violent Persons Commitment Act.
Kokoraleis was eligible for parole last month but remained in custody until officials say they can find an approved place for him to live.
Friday's announcement means Kokoraleis will be released if he finds an approved place to live. If he doesn't, he can't be held in prison beyond March 2019.
The Associated Press contributed to this report.