Jay Simon, 38, was found guilty of aggravated criminal sexual abuse.
Prosecutors say he molested a 10-year old girl during a sleepover at his home in Zion in 2006.
Simon had been honored several times for leading the number of DUI arrests at the Gurnee Police Department.
He has been on leave since 2008.
The Gurnee Police Department says it will now begin steps to fire Simon.