Kirsty Jones was 23 and just three months into a two-year round the world trip when she was raped and strangled in her hostel in Chiang Mai in August 2000.
It is feared that time is running out to catch her killers as Thai cases are closed after 20 years.
Her family’s local MP has therefore called for her belongings to be returned to Britain, so police here can carry out extensive testing to see if they hold any further clues to the identity of her killers.
Chris Davies, Brecon and Radnorshire MP, told BBC Radio Wales: “Kirsty’s belongings are still in Thailand. They haven’t even be sent home to her parents.
“We want them to come back here. We want to have further investigations carried out.”
Ms Jones’ (above) mother, Sue, has campaigned tirelessly for justice and has previously said that she felt that the Foreign Office were prioritizing diplomacy after they refused to release documents surrounding her daughter’s case.
The Liverpool University graduate’s family are due to join forces with the families of other young people who have died abroad to deliver a petition to Theresa May asking for better consular assistance in such circumstances.
These include the family of Christina Annesley, 23, a Leeds University History graduate, whose death on Koh Tao island just over three years ago remains unexplained and the sister of Hannah Witheridge who was raped and killed on Koh Tao in 2014.
Mr Davies said he has now written a letter of international request to have Ms Jones’ belongings sent home.
In 2013 Dyfed-Powys Police were given permission to forensically review evidence collected by Thai officers and analysis of DNA samples showed that they matched someone of south-east Asian origin.
Mr Davies said that if the clothes were returned further tests could be carried out.
“We have two years to do it. Time is running out for the Jones family,” the Conservative MP said.
“What they need now is justice. We sadly are not able to bring Kirsty back, but if there’s one thing we can deliver its justice and closure for the Jones family.”
When he raised the matter with Theresa May last year in the House of Commons last year she said that the British Government was unable to interfere in police investigations in another country.
By Hayley Dixon