Police investigating the cold case murder of a Perth woman more than 40 years ago have recovered the DNA of a mystery man.
Kerryn Tate, 22, was found dead by forestry department workers in the Canning Dam catchment area on December 30, 1979.
A reward of up to $1 million for information that leads to the conviction of the person or people responsible for the murder remains on offer.
Police today revealed the DNA breakthrough as they appealed for more information.
Detective Senior Sergeant Steve Potter said police are using "every technical means possible" available in Australia and overseas to identify the man behind the DNA, including Ancestry.com and family trees.
"Quite frankly, somebody in our community knows what happened to Kerryn," Potter said.
"We are asking people if they do suspect somebody that may have had something to do with what happened to Kerryn to let us know."
Tate's body was found in dense bushland about 800 metres from where she was house-sitting south of the Brookton Highway in Karragullen and about 40 kilometres from she was living on Barlee Street in Mount Lawley.
At the time, Tate was wearing a light-coloured blouse, dark blue jeans, a belt with a large metal buckle and sandals.
Two nights before her death, Tate attended a dance at the North Cottesloe Surf Life Saving Club with a friend on December 28.
She left the club at about midnight and spent the night with friends at a house in Swanbourne before getting a lift back to the Barlee Street address at about 11am on December 29.
It is believed she intended to travel to Karragullen afterwards to continue to house-sit for friends.
Police said Tate's movements from when she was dropped off to the time her body was found are unknown.
Potter said he is confident the special crime squad team will find the person behind the link.
"The first step will be to identify who that DNA sample is and we'll talk to that person and find out what their involvement is," he said.
Her family joined police in calling for help in solving the case.
"Although many years have passed since Kerryn's murder, just hearing her name or seeing her face still brings us to our knees and breaks our hearts again," the family said in a statement.
"Please stand up and give us the answers that we have been waiting our whole lives for - so we can at least understand why this happened."
Potter dismissed rumours Tate's death was linked to witchcraft, despite early media reports in 1979.
"I know it was reported very early," he said.
"There's not a lot of information that we've got that anybody really close to Kerryn was involved in witchcraft or the like.
"As we're working through people now, we may find some links to that.
"I think she had visited a bookshop that sold those sort of books at one stage."
Potter said there was a fire in the area at the time but police are confident Tate didn't die as a result of the blaze.
"She was described as being a girl who had a few close friends and many acquaintances, but also enjoyed her own company," Crime Stoppers WA said.
She often hitchhiked to wherever she went and was known to carry a black helmet with her in case she was offered a ride on a motorcycle.
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