The Tube Sock Killer
Overview
The name “Tube Sock Killer” refers to an unidentified person suspected of committing a series of unsolved killings in the isolated forests of western Washington during 1985. The crimes are more formally known as the Mineral, Washington murders or the Tube Sock Killings. They involved two couples who disappeared while visiting wooded recreational areas near Mineral, Elbe, Tule Lake and the Nisqually River in Pierce and Lewis counties.
The unusual signature connecting the cases was the discovery of white tube socks tied around the necks of the two female victims. Both women had been separated from their male companions, violently killed and abandoned in remote locations. The similarities led investigators to consider the possibility that a serial killer had targeted couples camping or traveling in the region. No person has ever been convicted of the murders, and it has never been conclusively established that all four deaths were committed by the same offender.
The Murders of Stephen Harkins and Ruth Cooper
On August 10, 1985, 27-year-old Stephen Alexander Harkins and his 42-year-old girlfriend, Ruth Eleanor Cooper, left their home in Tacoma for a weekend camping trip near Tule Lake in southern Pierce County. The couple enjoyed camping and planned to return in time for work at the vocational school they attended. They brought their dog with them.
When Stephen and Ruth failed to appear at school the following Monday, their families reported them missing. On August 14, hikers discovered Stephen’s body at a remote campsite. He was still inside his sleeping bag and had been shot in the head with a small-caliber firearm. The circumstances suggested that he may have been attacked while asleep or before he had an opportunity to defend himself.
The couple’s dog was found nearby and had also been shot to death. Ruth was nowhere in the immediate area. Her disappearance prompted an extensive search, but weeks passed without any sign of her.
On October 26, 1985, Ruth’s skull was discovered near the dead end of Eighth Avenue South in the Harts Lake area, approximately a mile and a half from the campsite where Stephen had been found. Searchers recovered the remainder of her body and her purse two days later, roughly 50 feet from the location of the skull.
A tube sock had been tied around Ruth’s neck. Reports concerning her autopsy described her death as the result of homicidal violence, with later accounts identifying a gunshot wound to the abdomen as the fatal injury. The separation of her remains was believed to have resulted from decomposition and animal activity rather than deliberate dismemberment.
The Disappearance of Diana Robertson and Mike Riemer
On the morning of December 12, 1985, 21-year-old Diana Lee Robertson, her 36-year-old boyfriend, Michael Lloyd “Mike” Riemer Jr., and their two-year-old daughter, Crystal, left their home for a trip into the mountains south of Tacoma. The family intended to find a Christmas tree near the Nisqually River. Mike, who trapped animals during the winter, also planned to check traps he had placed in the area.
Later that day, customers found Crystal standing alone outside a Kmart store in Spanaway, approximately 30 miles from the area her parents had planned to visit. The child could not provide authorities with her name or enough information to identify her family. She was placed in temporary foster care until relatives recognized her photograph during a television news report.
When Crystal was asked what had happened to her mother, she reportedly said that her “Mommy was in the trees.” Because she was only two years old and had limited verbal ability, investigators were unable to obtain a reliable account of who had taken her to the store or what she had witnessed in the forest.
Search teams attempted to locate Diana, Mike and Mike’s red 1982 Plymouth pickup truck. The rugged terrain and winter weather made the operation difficult. No trace of the couple was found during the initial search.
The Discovery of Diana Robertson
On February 18, 1986, a motorist discovered Diana Robertson’s body near an old logging road off State Route 7, south of Elbe. Her remains were partially covered by snow. Mike’s pickup truck was found nearby.
An autopsy determined that Diana had been stabbed 17 times. A tube sock was tied tightly around her neck, closely resembling the sock found around Ruth Cooper’s neck several months earlier. The matching detail became the most important apparent connection between the two cases.
Investigators found blood inside the pickup truck. A message written on a manila envelope and left on the dashboard read, “I love you, Diana.” Diana’s mother reportedly believed the handwriting belonged to Mike. The meaning of the message remains uncertain. It may have been written before the violence, during a confrontation or by someone attempting to make Mike appear responsible.
Mike had previously been accused of assaulting Diana in October 1985, although the couple reconciled before their December trip. Because Mike was missing when Diana’s body was found, investigators initially considered the possibility that he had murdered her, abandoned Crystal at the Kmart and fled. Authorities also explored the possibility that he had killed Stephen Harkins and Ruth Cooper.
There were serious problems with that theory. Mike had no apparent reason to murder Stephen and Ruth, and abandoning his daughter safely at a crowded store was difficult to reconcile with a plan to vanish permanently. Another possibility was that Mike had been attacked and killed by the same offender who murdered Diana and the first couple.
The Discovery of Mike Riemer’s Remains
More than two decades passed without a confirmed sighting of Mike. In March 2011, a partial human skull was found on an old logging road north of Mineral, within approximately a mile of the place where Diana’s body had been discovered. Dental and forensic comparisons identified the remains as those of Mike Riemer.
The discovery weakened the theory that Mike had escaped and created a new possibility that he was the fourth victim in the series. His cause and manner of death could not be conclusively determined because only a portion of his remains was recovered. Investigators were able to determine that he had not been shot in the head, but they could not establish whether he had been stabbed, strangled, struck or killed by some other means.
It is believed that Mike died on or shortly after December 12, 1985, the day he disappeared. His remains may have been overlooked during earlier searches because of thick vegetation, difficult terrain, snow and the large area investigators were required to cover.
Known and Suspected Victims
- Stephen Alexander Harkins, 27 — August 10, 1985 — Tule Lake area, Pierce County, Washington: Harkins was shot in the head while inside his sleeping bag at a remote campsite. His body was discovered on August 14, 1985. The couple’s dog was also found shot nearby.
- Ruth Eleanor Cooper, 42 — August 10, 1985 — Harts Lake and Tule Lake area, Pierce County, Washington: Cooper disappeared from the campsite where Harkins was killed. Her skull was found on October 26, and the remainder of her body was recovered on October 28. She had suffered homicidal violence, reportedly including a gunshot wound to the abdomen, and a tube sock was tied around her neck.
- Diana Lee Robertson, 21 — December 12, 1985 — Near Elbe, Pierce County, Washington: Robertson disappeared during a family trip to find a Christmas tree and check animal traps. Her body was found beside a logging road on February 18, 1986. She had been stabbed 17 times and had a tube sock tied around her neck.
- Michael Lloyd “Mike” Riemer Jr., 36 — December 12, 1985 — Mineral and Elbe area, Washington: Riemer disappeared with Robertson and their daughter. A portion of his skull was found north of Mineral in March 2011. His cause of death remains undetermined, but investigators have considered him a possible homicide victim.
Possible Related Cases
Investigators examined other killings involving couples who disappeared while traveling through rural Washington. Among them were Edward Smith and Kimberly Diane LaVine, a Kent couple who vanished in March 1985. Smith’s body was found in a gravel pit, while LaVine’s remains were recovered months later in sagebrush some distance away.
The Smith and LaVine case shared certain general characteristics with the Tube Sock Killings. A couple had disappeared together, the male victim was found before the female victim, and the woman’s body had been left some distance away. However, no tube sock was reported in that case, and investigators never established a definitive forensic connection to the Mineral murders.
Other violent offenders active in Washington during the period were also examined. Investigators compared criminal histories, locations, methods and known movements, but no suspect was conclusively connected to the evidence from both Tube Sock cases.
The Killer’s Possible Method
The circumstances suggest that the offender may have been familiar with the forest roads surrounding Mineral, Elbe, Harts Lake and the Nisqually River. These areas contain logging roads, isolated campsites and dense woodland where a person could approach travelers without being observed. The killer may have lived locally, worked in forestry or logging, hunted, trapped animals or frequently traveled through the region.
Stephen Harkins appears to have been attacked at the campsite, possibly while asleep. Ruth Cooper was removed from the immediate scene and killed or abandoned elsewhere. Diana Robertson was also separated from her male companion and left near a logging road. If Mike Riemer was murdered by the same person, his body was concealed or deposited far enough from Diana that it remained undiscovered for decades.
The offender may have used a firearm to gain control of the victims. The shooting of Stephen and the couple’s dog could have eliminated immediate resistance and prevented the dog from raising an alarm. Diana’s numerous stab wounds suggest a prolonged and intensely violent attack. The socks tied around the women’s necks may have been used as ligatures, restraints or deliberate signatures intended to mark the crimes.
Theories About Crystal Robertson
One of the case’s most enduring mysteries is how two-year-old Crystal arrived at the Kmart in Spanaway. The distance between the store and the mountain area makes it virtually impossible that she reached it without assistance. Someone must have driven or carried her there.
If Mike killed Diana, he may have left Crystal at the store to ensure that she was found before taking his own life or dying in the wilderness. If an unknown killer murdered both adults, that person may have spared the child and abandoned her in a public place. Another possibility is that a witness or uninvolved motorist encountered Crystal and left her at the store without contacting authorities, although no such person ever came forward.
The decision to leave Crystal alive may indicate that the offender did not want to kill a small child or believed that she was too young to identify him. Her survival also suggests planning. Whoever transported her had to travel from the forest to Spanaway while avoiding attention and then leave her where she would quickly be discovered.
Suspects and Investigative Difficulties
Mike Riemer was the most publicly discussed suspect before his remains were identified. His prior domestic violence allegation gave investigators a reason to examine him closely, but no physical evidence proved that he killed Diana. The discovery of his skull near the crime scene made it more plausible that he had also been attacked.
The investigation was hampered by the remote locations, delayed discoveries and exposure of the bodies to weather and wildlife. Ruth Cooper was missing for more than two months, Diana Robertson was not found until the following February, and Mike remained undiscovered for approximately 25 years. The passage of time damaged or destroyed biological evidence that might have identified an offender through modern DNA testing.
Investigators also had to determine whether the tube socks represented a genuine serial-killer signature or a coincidental feature. Tube socks were extremely common during the 1980s and could have belonged to the victims, the offender or another person. Nevertheless, finding similar socks tied around the necks of two women killed in the same rural region within four months was considered highly suspicious.
Unresolved Questions
It remains unknown whether the victims encountered the killer by chance or were deliberately followed. The offender may have watched campsites and logging roads for isolated couples, or he may have approached under the appearance of offering assistance. He may also have known one or more of the victims.
Authorities have never publicly established who wrote the note found in Mike’s truck, whose blood was present inside the vehicle or exactly where Crystal was separated from her parents. It is also uncertain whether Ruth and Diana were killed where their bodies were found or transported after death.
The greatest unanswered question is whether one person committed all four suspected murders. Stephen and Ruth were unquestionably homicide victims, and Diana was murdered in a strikingly similar setting. Mike’s death remains less certain because his cause of death could not be determined. The possibility that separate offenders committed the two attacks has never been completely eliminated.
Current Status
The Tube Sock Killings remain unsolved. The unidentified offender has never been arrested, publicly named or conclusively linked to another crime. No confession, eyewitness identification or definitive piece of forensic evidence has established who attacked the couples.
The case continues to attract attention because of its unusual signature, the survival of a young child and the decades-long mystery surrounding Mike Riemer’s disappearance. Although the offender is commonly called the Tube Sock Killer, investigators have never proved that a single serial killer was responsible. Stephen Harkins, Ruth Cooper, Diana Robertson and possibly Mike Riemer remain at the center of one of Washington’s most disturbing unresolved murder investigations.
