Dark Hollow

Description for DARK HOLLOW by John Connolly:

Haunted by the murder of his wife and daughter, former New York police detective Charlie Parker retreats home to Scarborough, Maine, to rebuild his shattered life. But his return reawakens old ghosts, drawing him into the manhunt for the killer of yet another mother and child. The obvious suspect is the young woman's violent ex-husband. But there is another possibility--a mythical killer who lurks deep in the dark hollow of Parker's own past, a figure that has haunted his family for generations: the monster known as Caleb Kyl.

This is #2 in A Charlie Parker Thriller.