Stolen Time — Patrick J. O'Brian

A serial killer is targeting cops in a Chicago suburb, and Detective Joe Garrett is determined to discover his identity before another one of his fellow police officers is murdered. A hardened investigator, Garrett follows a string of murders spanning four decades, once every five years to the date. With his own personal problems, and the holidays closing in, Garrett discovers time is a more precious commodity than he ever anticipated. Every clue he finds seems to lead to a dead end. Choosing to research potential victims by riding with the patrolmen he figures are prime targets, the investigator befriends a salty officer, developing a unique relationship based on their parallel careers. Garrett must ultimately unravel the politics hindering his investigation and discover the killer's true motives before someone he knows becomes the last victim in a gruesome ritual coming full circle.