A southwestern Illinois man has been sentenced to 18 years in prison for sexually assaulting a 10-year old girl.  The Belleville News-Democrat reports that 30-year old Frederick Lyles of East Saint Louis must serve at least 15 years and three months of the sentence imposed Monday in Saint Clair County.  Prosecutors sought a 30-year term.  Lyles pleaded guilty last month to one count of predatory criminal sexual assault.  Prosecutors dropped a similar felony count.  During his sentencing hearing, Lyles apologized for what he did and said he accepts responsibility.  He says he was sexually molested as a child.  After his prison term, Lyles must register as a sex offender for the rest of his life.