The British partner of a south-east Asian woman found dead in a Dales stream in 2004 is suspected of having vital information about her disappearance.
Police have never identified the mystery female, aged between 25 and 35, since her body was discovered by walkers in a stream near Pen-y-Ghent, one of the Three Peaks.
Cold case teams think she was taken to the remote location in Ribblesdale in a 4x4, and was found more than a mile from the nearest road dressed only in jeans and socks.
Investigating officers have now told the BBC that she could have been a 'Thai bride' who had come to the country to marry a British man.
DNA analysis found that she was originally from south-east Asia but particle samples revealed she had been in the UK for two years, and had spent time in Lancashire and Cumbria.
A cause of death has never been established, but she died between August 31 and September 13, 2004, and was found a week later.
Adam Harland from the joint North Yorkshire and Cleveland Police cold case review team said it was possible she could have been suffocated.
They are working on the hypothesis that she was dead when she was driven to the scene and could have been killed at home.
"The lady is possibly some sort of Thai bride. Not meaning that she comes from Thailand, but she is a lady who has taken up a relationship with a white British man, and come back to the UK.
"That would probably mean that her partner is older than her, and quite likely has led a more solitary individual life prior to their relationship taking place."
"Whoever her partner was in the last days of her life is the person we'd like to speak to."