A Cold Dark Place by Gregg Olsen, (Emily Kenyon Series, Book 1) From Books in Motion.com

The Seeds of Evil...In a secluded farm house in the Pacific Northwest, a family has been slaughtered and a teenage son has disappeared. Single mother and cop, Emily Kenyon spearheads a dark hunt for a killer. But Emily's teenage daughter Jenna is one step ahead of her...are planted in...Jenna knows the boy suspected of murdering his family and wants to help him perhaps too much. Then another family is butchered, this time in Iowa. And on the heels of this brutal slaying, another follows in Salt Lake City. Eerie similarities link the crime scenes. But an even darker connection threatens to claim even more victims...A Cold Dark Place...As Emily fits the puzzle pieces together, she realizes the danger surrounding her daughter is worse than she'd imagined. Now, in a desperate race to save Jenna, Emily must match wits the most cunning, diabolical killer she's faced yet in her career a killer who just placed her and her daughter on the top of the list...