Roadside Crosses - Jeffery Deaver

A highway patrol trooper notices something strange on the side of the road: a homemade cross, fashioned as a memorial. Except the date being 'remembered' is the following day - the day the police find a kidnapped teenage girl in the trunk of a car, left for dead. Special Agent Kathryn Dance, kinesics expert with the California Bureau of Investigation, is on the case. The teenage victim points her to an online community where criticism is vicious. It looks as though one teen has finally snapped. Then further crosses appear. Now Dance must race against the clock to find the attacker before he can carry out his deadly plans for revenge . . . in the cyber world and the real.