On December 12, 1985, 21-year-old Diana Robertson went into the mountains near Tacoma, Washington with her 36-year-old boyfriend, Mike Riemer, and their two-year-old daughter, Crystal, to find a Christmas tree and for Riemer to check animal traps. That afternoon Crystal was found wandering alone outside a Kmart in Spanaway and told people that Mommy is in the trees. A search initially turned up nothing for two months.

On February 18, 1986 a walker found Diana’s body deep in forest near Elbe. She had been stabbed 17 times and a tube sock was tied tightly around her neck. Riemer’s pickup truck was nearby with bloodstains on the front seat and an envelope reading I love you, Diana, but Mike Riemer was missing and a warrant was issued for his arrest. Investigators noted Riemer had a documented history of domestic violence and an active restraining order.

Police later linked Diana’s killing to another double slaying 15 miles away; Ruth Cooper was also found with a tube sock knotted the same way, raising the possibility of a serial offender. In 2011 hikers found a partial skull about a mile from Diana’s location; dental records matched it to Mike Riemer, though his cause of death could not be determined. No arrests have been announced.

Does anyone have information about Diana, Mike, or their movements that winter?