The Dead Tracks (A David Raker Mystery, Bk. 2) by Weaver, Tim

Seventeen-year-old Megan Carver was an unlikely runaway. A straight-A student from a happy home, she studied hard and rarely got into trouble. Yet six months on, she still hasn't been found.
 
Missing persons investigator David Raker knows what it's like to grieve. He knows the shadowy world of the lost, too. So when he's hired by Megan's parents to find out what happened, he recognizes their pain--but knows that the darkest secrets can be buried deep. And Megan's secrets could cost him his life.
 
Raker's investigation takes him through a confounding string of surprises and deceptions. People close to Megan turn up dead. Others remain too terrified to talk. And soon the conspiracy of silence leads Raker towards a forest on the edge of the city. A place with a horrifying past as the hunting ground for a twisted serial killer. A place known as the Dead Tracks. . . .