When a young family ventures into a remote Washington forest in search of the perfect Christmas tree, a dark mystery unfolds. Parents go missing, a child is found wandering alone in another town and all of Washington state wonders whether a serial predator may be waiting in the woods in this episode of Last Seen Alive.

Sources used to research this episode:

Diana Robertson (Unsolved Mysteries)

Mineral: Diana Robertson (Washed Away Podcast)

Parents Missing (Associated Press)

Father Presses Hunt for Missing Couple (Associated Press)

Woman’s Body Found (Associated Press)

Woman’s Body Discovered (The Spokesman-Review, Feb. 20, 1986 ed.)

Body Identified As Trapper’s Girlfriend (Associated Press)

Woman Was Slain, Her Boyfriend’s Still Missing (Associated Press)

Puyallup Father Continues Hunt for Clues in Couple’s Disappearance (Associated Press)

Police Say Boyfriend Could Be Slaying Suspect (Seattle Post-Intelligencer / George Foster)

Bureau of Justice Statistics Selected Findings: Female Victims of Violence (Bureau of Justice Statistics)

Skull Discovery Revives Washington Mystery (The Seattle Times)

Mystery Lingers: Discovery of Trapper’s Skull Adds Clue to Couple’s 1985 Disappearance (The Olympian / Stacey Mulick)

Discovery of Skull Raises New Questions About 1980s Murders (Stacey Mulick / The News Tribune)

Are Cases Tied? (Ellensburg Daily Record)

Authorities Try to Identify Skull (The News Tribune)

Headless Body May Be Missing Woman (The News Tribune)

Death Listed As Suicide (The Olympian)

Baffling Deaths Haunt County (Dave Hendrick / The Olympian)

If you know anything about the deaths of Diana Robertson or Michael Riemer, please contact the Lewis County Sheriff’s Office at: 360-748-9286.