Without Due Process by J.A. Jance

When a Seattle police officer named Ben Weston and his family are murdered in their home, the members of the police department are deeply affected. Homicide detective J.P. Beaumont is called out to the crime scene with his partner, Al Lindstrom, and is given the job of working on the case of Adam Jackson, who was sleeping over at the Websters' and was killed that evening too. Soon, it becomes clear that Ben possibly had secrets in his professional and personal lives that could be related to motives for the crime. Will Beaumont be able to bring the family's killer to justice? Without Due Process is the 10th book in the long-running J.P. Beaumont series and was first published in 1992.