This is the first of the Georgia Davis mysteries, which of course I read after having read the fourth, the most recent. This is not generally the order to read a mystery series in, but it worked out well this time.
Georgia is a Chicago cop, currently suspended for egregious violations of procedure, and working as a private investigator. Her former and perhaps future boss, Dan O'Malley, refers a client to her, Ruth Jordan, sister of Cam Jordan, a mentally challenged man charged with murdering a high school girl in the woods, during an unofficial high school party.
Cam is a registered sex offender, but his past offenses are public masturbation, and he's never done anything remotely violent. Yet the case against him is moving strangely fast--a few weeks for things that normally take months. What's going on?