The Mineral, Washington Murders

Overview

The Mineral, Washington murders, infamously dubbed "the Tube Sock Killings," represent a chilling series of unsolved homicides that unfolded in the remote terrain of Lewis and Pierce County, Washington, in 1985. This dark chapter in Washington's history garnered widespread media attention and was notably featured on the television series Unsolved Mysteries in 1989, captivating audiences with its eerie details.

Quick Facts

• Victims: 4–6
• Span of Crimes: August 10 – December 12, 1985 (possibly as early as March 1985; undetermined)
• Location: Mineral, Washington, USA
• Suspected Assailant: Unknown

The Case

Harkins and Cooper

The investigation began on August 10, 1985, when 27-year-old Steven Harkins and his girlfriend, 42-year-old Ruth Cooper, set out for a weekend camping trip at Tule Lake in Pierce County. They were looking forward to a serene escape from their busy lives in Tacoma, Washington. However, when they failed to return for work at their vocational school that Monday, their families became alarmed and reported them missing.

Four agonizing days later, on August 14, hikers stumbled upon Harkins' body near a secluded campsite. The gruesome scene revealed he had been shot in the head, and shockingly, his body was still wrapped in a sleeping bag, suggesting he had been taken in his sleep. Nearby, searchers found Harkins' pet dog, also shot dead, heightening the horror of the discovery.

At that time, investigators began to speculate that this case might be linked to another double murder that occurred earlier that year. Edward Smith and Kimberly Diane La Vine, a couple from Kent, Washington, had been abducted, murdered, and disposed of in a gravel pit near the Columbia River in March 1985. The connections between these cases began to complicate the investigation.

The plot thickened on October 26, when a skull was found at a dead-end near Harts Lake, about 1.5 miles from where Harkins' body was discovered. Dental records confirmed the skull belonged to Ruth Cooper. Just two days later, on October 28, her body was located, along with her purse, just 50 feet from her skull. The autopsy revealed that Cooper had met a similarly violent fate, dying from a gunshot wound to the abdomen. Even more eerily, a tube sock was found tied around her neck, a detail that would become a hallmark of the murders.

Following the recovery of Cooper’s remains, Crime Stoppers publicized the case in hopes of garnering leads that could lead to the arrest of the perpetrator.

Riemer and Robertson

Fast forward a month later, on December 12, 1985, and we find Mike Riemer, 36, and his girlfriend, Diana Robertson, 21, along with their 2-year-old daughter, Crystal, heading from Tacoma to Pierce County. They were on a quest to find the perfect Christmas tree, but Riemer, an animal trapper, also intended to check on traps he had set in the area.

That evening, a haunting scene unfolded: shoppers at a Kmart store, about 30 miles north in Spanaway, were shocked to find little Crystal standing alone outside the store entrance. She was placed in temporary foster care, and it took two days before her maternal grandmother recognized her from local news broadcasts. When asked about her mother, the bewildered toddler said her "Mommy was in the trees," a statement that would leave investigators puzzled as they searched for clues.

Despite extensive ground and aerial searches, no sign of Riemer or Robertson emerged. The investigation remained stagnant until February 18, 1986, when a motorist discovered Diana's body half-buried in snow near a logging road off Washington State Route 7, just south of Elbe. The weather had been brutal, with six inches of snow complicating the search efforts.

Not far from her body, Riemer’s red 1982 Plymouth pickup truck was located. Inside, police found a note on the dashboard that read, "I love you, Diana," penned on a manila envelope. Diana's mother believed the handwriting matched Riemer’s. Bloodstains on the truck seat only deepened the mystery. An autopsy revealed Diana had been stabbed seventeen times, and like Cooper, a tube sock had been tied around her neck.

Due to Riemer's sudden disappearance, investigators leaned towards the theory that he may have been involved in Diana's murder, possibly abandoning their daughter at the Kmart and fleeing the scene. However, a solid motive remained elusive. Some theorized that Riemer could have also been a victim of the same killer who murdered Cooper and Harkins, adding another layer of complexity to the investigation.

In February 1986, just after the discovery of Diana's body, the Seattle Post-Intelligencer revealed that Riemer had faced domestic assault charges against Diana just a few months prior, in October 1985. However, by December, the couple had reconciled, and their sudden disappearance sparked further intrigue.

2011 Development

A significant development occurred on March 26, 2011, when hikers stumbled upon a partial human skull in the same vicinity where Robertson's body had been found. It was later identified as belonging to Mike Riemer. Lewis County investigators speculated that Riemer could also have been a homicide victim, although determining the cause of death proved impossible. Authorities ruled out a gunshot wound to the head based on the condition of the skull.

Media Depiction

The haunting nature of the Mineral murders captivated national attention, and in September 1989, the case was highlighted on Unsolved Mysteries, further embedding it into the annals of true crime lore.

Sources

• The Associated Press (April 11, 2014). "Skull discovery revives Washington murder mystery". The Seattle Times.
• "Are cases tied?". Ellensburg Daily Record. August 28, 1985.
• "Murder victim identified". The Dispatch. November 6, 1985.
• "Woman's body discovered". The Spokesman-Review. February 20, 1986.
• Weathersby, Jeff (December 12, 1986). "Officials still seek trapper a year later". The News Tribune.
• Foster, George (February 21, 1986). "Police say boyfriend could be slaying suspect". Seattle Post-Intelligencer.
• Stack, Robert (September 6, 1989). "Unsolved: Mike Riemer and Diana Robertson". Unsolved Mysteries.
• Penhale, Ed (December 17, 1985). "Toddler provides no clues to parents' disappearance". Seattle Post-Intelligencer.
• "Officers baffled over couple's disappearance". The Eugene Register-Guard. December 17, 1985.
• Erickson, Jim; Lane, Bob (February 20, 1986). "Body found on logging road probably is Puyallup mother". The News Tribune.
• McNerthney, Casey (April 12, 2011). "Police link skull to 1985 cold case". Seattle Post-Intelligencer.
• The Associated Press (April 14, 2011). "Skull Found in Washington Revives Unsolved Murder Mystery". Fox News.
• Pearson, Adam (April 12, 2011). "Remains those of Tacoma man missing since 1985". The Spokesman-Review.
• "Mystery lingers: Discovery of trapper's skull adds clue to couple's 1985 disappearance". The Olympian. April 13, 2011.