A hiker's discovery of a skull near Mineral has revived a murder mystery from the 1980s, and sheriff's detectives from Lewis and Pierce counties are taking another look at the deaths of two couples.

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Within four months in the mid-1980s, three people were found slain and a fourth went missing within 15 miles of each other in remote, wooded areas of Pierce and Lewis counties.

Two of the dead were women, and tube socks were found tied around their necks.

The evidence made detectives wonder whether the deaths were connected, but the theory didn’t take them far and didn’t lead to any arrests or resolutions in the cases.

“It may just be coincidence that tube socks were used,” Art Anderson, a retired Pierce County sheriff’s homicide detective, said Wednesday.

Anderson investigated both cases – the slayings of Ruth Cooper, 42, and her boyfriend, Steven Harkins, 27, in August 1985; and the disappearance four months later of Diana Robertson, 21, and her boyfriend, Michael Riemer, 36.

The cold cases are getting a fresh look after the discovery March 26 in a wooded area near Mineral of a partial human skull later determined to be Riemer’s.

The skull solved a piece of the puzzle concerning Robertson’s slaying – the whereabouts of Riemer.

But it renewed other questions, including what happened to the Puyallup couple and how their 2-year-old daughter, Crystal, ended up alone at a Spanaway Kmart later on the day they were last seen.

Detectives from the Lewis County and Pierce County sheriff’s departments are again talking to each other about the two cases, just as they did in the mid-1980s.

The investigators will review the evidence to determine whether advances in technology could provide new clues into what happened.

“We will definitely look back into this case,” Stacy Brown, chief deputy for the Lewis County Sheriff’s Office, said of the Robertson-Riemer investigation. “There are so many theories circling around.”

One is whether there’s a connection to the Cooper-Harkins case.

The two left their East Side Tacoma home the evening of Aug. 10, 1985, for a weekend camping trip near Tule Lake in southern Pierce County.

Four days later, a passer-by found Harkins’ body near a remote campsite. He’d been shot in the head while in his sleeping bag, according to past News Tribune stories.

Searchers later found the body of the couple’s dog, which also had been shot.

Hunters walking along the dead end of Eighth Avenue South found Cooper’s remains Oct. 26, 1985, in the same area as Harkins’ body had been found.

Her skull was found about 50 feet from the rest of her body and her purse. A tube sock had been tied around her neck.

Investigators ruled she’d died of “homicidal violence.”

Two months later, on Dec. 12, Riemer, Robertson and their daughter went to check his animal traps in the Nisqually River area. The parents never returned, but their daughter, dazed but unharmed, mysteriously showed up at the Kmart store.

A man walking his dog on Feb. 18, 1986, found Robertson’s remains buried in the snow along a logging road between Elbe and Mineral. She had been stabbed multiple times, and a tube sock was tied around her neck.

Riemer’s truck was near Robertson’s body, but he was nowhere to be seen.

Several searches were conducted, but no trace of Riemer was found until last month, when a hiker discovered the partial skull within a mile of where Robertson’s remains had been found 25 years earlier.

Because he’d disappeared, Riemer long had been considered a person of interest in Robertson’s death. Others thought he, too, was the victim of foul play.

Lewis County investigators found other evidence near the partial skull but have declined to say more, Brown said. They also discovered a heavily weathered identification card but don’t know whose it is or whether it’s connected to Riemer.

Anderson, who retired in 2000 after 33 years with the Pierce County Sheriff’s Department, said the skull’s discovery brought back old memories of the cases.

“It sparks your memory,” he said. “Both of those were very interesting and whodunits.”

Information from: The News Tribune, http://www.thenewstribune.com