Thai police have confirmed that DNA tests link two fishermen with the rape and murder of British holidaymaker Katherine Horton.
The men, aged 23 and 24, were arrested on the island of Koh Samui close to the beach where the 21-year-old was last seen on 1 January.
They were flown to Bangkok on Monday where the DNA tests were carried out.
A post-mortem examination suggested the Reading University student from Cardiff was raped and beaten before her death.
The fishermen were arrested after police began to question fishermen whose boats were moored in the bay where Miss Horton's body was discovered a week ago.
The fishermen were flown to Bangkok to undergo DNA tests
A third year psychology student, Miss Horton was due to return home this week after a fortnight in Thailand.
She had been with friends on Lamai beach on 1 January, close to the bungalows they had rented, when she is said to have wandered away to wish her mother happy new year on her mobile phone.
Her body was discovered in the bay some 12 hours later.
Her travelling companion and university friend Ruth Adams said on Monday that Miss Horton's death had left a "huge void" in her life.
Miss Adams added: "My words cannot express the loss and devastation that I feel knowing I have lost my best friend."
The two men arrested in Thailand are expected to be formally charged with rape and murder at a local court in the next few days.
They have told police that they were drunk at the time and had been watching pornographic films.
Police Major Asawin Khawanmuang told reporters at police headquarters in Bangkok: "The suspects have admitted to raping and killing the British tourist, but we have brought them to Bangkok for DNA testing to be sure."
Miss Horton was staying with a friend in bungalows on Lamai beach
On Saturday a British couple who had found her mobile telephone on the sand returned to the island to assist the investigation.
The BBC's Kylie Morris said there had been government pressure on police to solve the case as quickly as possible.
"The island depends on the tourism trade - authorities were fearful of the impact the violent attack would have," she said.
On Friday, Thai prime minister Thaksin Shinawatra called on investigators to find those responsible for her death as quickly as possible but also urged them to be prudent.
Miss Horton's body was flown back to the UK over the weekend and a second post mortem examination was due to be carried out by a Home Office pathologist in Cardiff on Monday.