Desperation point The devil's cove trilogy, book 2.

Her son was the victim. Wasn't he? Devil's Cove used to be a safe place to live. Until a serial killer was discovered hiding in its midst. Now, as the Cornish community deals with the aftermath, Carrie must face the fact that her missing son may be implicated in the grisly crimes. Meanwhile, crime writer Aaron Black is intent on saving his flagging career by writing a book about the murders. But he needs Carrie's help and he'll do anything...