Just two weeks before Christmas, 1985, a young toddler is found wandering alone outside a Kmart in western Washington. Her parents couldn't be found anywhere. A few days later, the young girl - named Crystal - was reunited with her grandmother. There was only one clue that Crystal could offer to the location of her missing parents:

"Mommy is in the trees."

Almost 40 years later, those words still haunt our hearts like a bitter wind - because they are an emblem of not only one, but four, unsolved murders that may be the work of a serial killer.

The first case: Steven Harkins and Ruth Cooper

Let's step back in time a few months before Crystal's parents disappeared. In August of 1985, 27-year-old Steven Harkins and his 42-year-old girlfriend Ruth Cooper left Tacoma for a weekend camping trip near Tule Lake in Pierce County. They did not return on Monday, however, and were reported missing.

Four days after they had left for their trip, hikers found Steven's body in a sleeping bag near a Tule Lake campsite; the pet dog was found nearby. Both Steven and the dog had been shot, presumably at night given Steven's body position.

Ruth Cooper, Stephen Harkins, and a map of the Tule Lake area
Ruth Cooper, Stephen Harkins (Map: Google)

But where was Ruth Cooper? Searchers could not immediately locate her body. It wasn't until late October that a skull was found about a mile and a half from where Steven's body had been found. The skull was identified as Ruth's, and two days later, her body and purse were located about 50 feet away. There was one notable detail about Ruth's body: a tube sock had been tied around her neck.

Law enforcement wondered if the couple's murders were connected to the case of Edward Smith and Kimberly Diane La Vine, who were abducted from Kent. Smith and La Vine's bodies were later found in a gravel pit near the Columbia River earlier that year. However, a new case just months later would have them rethinking that theory.

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The second case: Mike Riemer and Diana Robertson

As Christmas approached, 36-year-old Mike Riemer and 21-year-old Diana Robertson, along with their 2-year-old daughter Crystal Robertson, left Tacoma to head to the forests near Mineral Lake. Riemer & Robertson intended to find a Christmas tree, as well as check traps that Riemer had previously set in the area.

It was just later that evening that young Crystal was found outside a Kmart in Spanaway, and we return to the start of this mystery.

Mike Riemer and Diana Robertson; an approximate map of the body's location
Mike Riemer, Diana Robertson (Map: Google)


Searches for the couple and their red Plymouth pickup truck were unsuccessful. It wasn't until February 18 when some answers were found, as a passing motorist spotted Diana's body in the snow off a logging road in Mineral, Washington, just off State Route 7. Diana had been stabbed repeatedly and also had a tube sock tied around her neck.

Riemer's truck was also found near her body, but Riemer would not be found - at least not for a few decades. In the meantime, investigators and the public speculated that Mike Riemer had murdered his girlfriend and then abandoned their daughter at the Kmart. He had previously been charged with domestic assault in October 1985, but the couple had decided to try their relationship again by the time of the trip.

newspaper clippings of headlines related to the tube sock murders
Ellensburg Daily Record / Eugene Register-Guard / The Spokesman-Review / The News Tribune

So did Mike Riemer commit the murder? We still don't know - but we do have one more clue. In March 2011 - 25 years after Diana's murder - Mike's skull was found within a mile radius of where his girlfriend's body had been found. His cause of death could not be determined, though a gunshot wound to the head was ruled out. Lewis County investigators indicated Riemer might have been a victim as well, but they did not share additional evidence they claimed to have recovered from the scene.

The "Tube Sock" murders become a Washington true crime tale

The cases are known either as the Mineral Washington murders or as the "Tube Sock" Murders, due to the signature state both women's bodies were found in. Despite the concern that Mike Riemer might have been the killer, there was still indication that these cases were likely connected.

Although it's certainly possible that Diana's body was set up in a "copycat" crime, there was one other key detail that pointed to the connection: the crime scenes were only about 15 miles apart as the crow flies. It's about a thirty-minute drive at most on the main roads - but anyone familiar with the area could easily traverse back roads or hike, especially over a several-month period.

A map showing the distance between two murder scenes
Google, Canva

Yet the lack of any additional known victims with this tube sock connection, or in the area, also hints that the cases may be well and truly disconnected. If they are, it is certainly a bizarre coincidence.

The Unsolved Mysteries episode featuring the Tube Sock Murders

In 1989, the TV show Unsolved Mysteries covered these two murder cases. You can watch the full episode below - or if you just want to watch about this case, it's the first story of the episode.

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