On a cold December day in 1985, 36-year-old Mike Riemer, a White male, vanished from the rugged landscape of Pierce County, Washington, leaving behind a chilling mystery that would endure for decades. On December 12th, Riemer, his 21-year-old girlfriend Diana Robertson, and their two-year-old daughter, Crystal, ventured into the woods. The family outing, intended for finding a Christmas tree and checking Riemer's animal traps, took a dark turn, marking the beginning of a complex and haunting
case.
Later that day, the first sign that something was amiss emerged when young Crystal was found alone and wandering outside a Kmart in Spanaway, some 30 miles away from where her parents were last believed to be. The little girl, unable to articulate what had happened, could only offer a cryptic and heart-wrenching clue to investigators, stating that her "mommy is in the trees." A massive search was launched for the missing couple. Two months later, in February 1986, the grim discovery of Diana Robertson's body on a remote logging road confirmed the worst fears. She had been brutally stabbed seventeen times, and a tube sock was tied around her neck. Nearby, authorities located Riemer's red Plymouth pickup truck. Inside, on the dashboard, was a manila envelope with the handwritten words, "I love you, Diana," believed to be in Riemer's writing. Bloodstains were also found on the truck's seat.
With Riemer nowhere to be found, he immediately became the primary suspect in Robertson's murder. Investigators theorized that he had killed his girlfriend, abandoned their daughter, and fled. This suspicion was fueled by a prior domestic assault charge against him in October 1985, although the couple had reportedly reconciled. Some even speculated that Riemer could be responsible for the murders of another couple, Steven Harkins and Ruth Cooper, who had been killed in the same area in August of that year. Ruth Cooper was also found with a tube sock tied around her neck, linking the cases and giving rise to the name, the "Tube Sock Killings."
For over two decades, Mike Riemer's fate remained a mystery. While law enforcement considered him a person of interest, his family and friends maintained that he too was a victim of foul play. Their belief was tragically validated in March 2011, when a hiker discovered a partial human skull in an area within a mile of where Diana Robertson's body had been found. Dental records confirmed the remains belonged to Mike Riemer. The condition of the skull allowed authorities to rule out a gunshot wound to the head, but a definitive cause of death could not be determined. The discovery of Riemer's remains shifted the focus of the investigation, suggesting he may have been a victim of the same killer who murdered his girlfriend and the other couple. However, without a clear cause of death, authorities could not completely rule out the possibility that he had taken his own life after killing Robertson. The case remains unsolved, with no arrests made and no definitive suspect identified, leaving the intertwined deaths of Mike Riemer and Diana Robertson a dark and unresolved chapter in the history of Pierce County.
