A prospector whose body was found down an abandoned mineshaft in Western Australia was murdered but the death of his wife remains a mystery, a coroner has found.
Raymond Kehlet, 47, and Jennie Kehlet, 49, never returned from a March 2015 prospecting trip to Sandstone, about 660km north of Perth.
Mr Kehlet's body was discovered about a month later, some 1.8km from their camp site, but his wife's remains have never been found.
The couple's friend and colleague Graham Milne - the last known person to see the couple alive - was a suspect but has never faced charges.
In findings published on Friday, coroner Ros Fogliani found Mr Kehlet - who had injuries to his face, neck and right hand - had been murdered "by a person or persons unknown".
The coroner made an open finding in regards to Ms Kehlet's death, saying it was impossible to determine how she died in the absence of her remains being found.
"It does not follow, from my finding in respect of Ray's manner of death, that Jennie's death was violent or as a result of trauma," the coroner said.
"Jennie might have managed to escape immediate danger and then become disoriented and lost. It cannot presently be known."
Ms Fogliani said a referral would be made to the director of public prosecutions.
While Mr Milne had been the subject of considerable publicity, she stressed that no person had been identified in connection with a possible offence.
"It is important for me to state that the referral ... is not made by reason of any belief that I have formed concerning any action, or omission, on the part of Mr Milne in relation to Ray or Jennie," she said.
Mr Milne was granted immunity so his evidence cannot be used against him in any future criminal proceedings.
He testified the last time he saw the couple they were chasing after their dog, Ella, on March 21.
Mr Milne said he spent 18 hours prospecting alone, then returned to the campsite in the early hours of March 22 and drove home.
Ms Fogliani found it was unlikely Mr Kehlet had accidentally fallen down the mineshaft, saying expert medical evidence pointed to him having sustained serious injuries and stood in a pool of his own blood shortly before his death.
"I am satisfied that Ray came to harm at the base of the mineshaft," she said.
"His death was violent and attributable to trauma, from injuries sustained as a result of the actions of a person or persons unknown."
A statement issued by the Kehlet family welcomed the coroner's findings, saying they hoped prosecutors would "pursue justice for Ray and Jennie".
Ms Kehlet's daughter Kelly Lee described the couple as inseparable, saying it was "beyond belief that anyone would ever want to hurt such loving, generous souls".
"We want to bring our mum home," she said.
WA Police said the Kehlets' deaths continued to be investigated by homicide detectives and a $250,000 reward was available.
"We acknowledge the sad impact their deaths continue to have on Ray and Jennie's families, and detectives remain in close contact with them," the statement said.
