On Easter Sunday, April 16, 2006, 57-year-old Joseph Lewis Gray was shot and killed in his Milo, Maine home while resting on his living room couch. His wife, Janice, was awakened by their dogs and saw a figure in a black jacket at the front door before a gunshot struck Gray. He urged her to call for an ambulance; a second shot rang out as she hid on the floor and officers arrived, but Gray died before help could reach him.

Investigators linked Gray’s slaying to a second killing hours earlier that same day: 24-year-old William Elliott of Corinth was also shot dead at his home. Both men appeared on Maine’s public sex offender registry, and police say that connection shifted the inquiry from random violence toward a targeted motive. A vehicle registration provided by a witness led investigators to 20-year-old Stephen Marshall of Nova Scotia; Marshall’s father lived in Maine and the pickup traced to the family was abandoned before Marshall boarded a bus to Boston. When police intercepted that bus, Marshall died by suicide, and authorities say he had compiled a list of names from the sex offender registry that included Gray and Elliott.

What details about the killer’s movements before and after the shootings might still help explain how these homes were selected?