The Scarecrow by Michael Connelly

Forced out of the Los Angeles Times amid the latest budget cuts, newspaperman Jack McEvoy decides to go out with a bang, using his final days at the paper to write the definitive murder story of his career. He focuses on Alonzo Winslow, a 16-year-old drug dealer in jail after confessing to a brutal murder. But as he delves into the story, Jack realizes that Winslow's so-called confession is bogus. The kid might actually be innocent. Jack is soon running with his biggest story since The Poetmade his career years ago. He is tracking a killer who operates completely below police radar--and with perfect knowledge of any move against him. Including Jack's.