THE FOREVER WITNESS

A cold-case hunt for a killer brought down by old-fashioned gumshoe work and lots of modern science.

In 1987, Canadian couple Tanya Van Cuylenborg and Jay Cook traveled from Vancouver to Seattle to purchase furnace equipment for his heating business. They made their way across the Olympic Peninsula, which, Humes writes ominously, “would take them through some of Washington State’s most remote and sparsely populated terrain.” They never made it home, both murdered by an unknown person fleetingly seen along their path. It took decades for police detectives to arrive at a suspect, working with what the author terms an “unlikely source,” a “self-taught genealogist” who worked with the PBS series Finding Your Roots With Henry Louis Gates, Jr. and who sussed out the killer’s identity by building a family tree. There were plenty of choices at first, including serial murderers such as the Green River Killer and Spokane Serial Killer, that needed to be narrowed down, but it took a paper cup carelessly dropped from the chief suspect’s truck to make the link to familial DNA. After the suspect was arrested, his mother-in-law said flatly, “I’m not surprised in the least,” for what emerged was a typical portrait: a bullied child, bright but disaffected, a “man at times consumed by anger yet desperately seeking approval.” The author then shifts the scene to a second arena in which the prosecuting attorney was working to establish “a coherent narrative that explained what happened, when and where,” and then trying to prove this with three-decade-old evidence. With side glances at other cold cases, Humes serves up a detailed but not overburdened exercise in investigative and legal logic that would have seemed ironclad save for an unforeseen technicality. About that, he writes, “finality is elusive in the justice system,” ending his book on an inconclusive note.

A well-paced true-crime procedural that offers new twists on old methods of police work.