Police in Thailand investigating the murder of a British student found dead on a beach believe she was raped.
Katherine Horton was last seen phoning her mother on 1 January
Katherine Horton, 21, from Cardiff, was attacked with a blunt instrument and left to drown in the sea off the island of Koh Samui.
The Reading University student was last seen on the beach on the evening of 1 January, talking on her mobile phone.
Her father, Ian, and older brother Christopher arrived in the Thai capital, Bangkok, on Wednesday.
The results of a post-mortem examination had already shown that Miss Horton's clothing was dishevelled and that she had suffered bruising as well as head and other internal injuries.
Miss Horton was staying with friends at Lamai beach
Having examined the report from a forensic scientist in Bangkok, Thai Police said on Wednesday that they were investigating the likelihood Miss Horton had been raped before being killed.
"Our investigation is focusing on rape," Lieutenant Colonel Thanongsak Aksornsom of Samui police confirmed.
Officers have now begun to carry out DNA testing on people who had met Miss Horton.
The third-year psychology student had flown to Thailand on 27 December with university friends for a short break. She had been due to return home to her family home in the Thornhill area of Cardiff next week.
She was last seen alive on the evening of 1 January where she had been with a group of friends on Lamai beach on the island.
At some point, Miss Horton is reported to have wandered away from them as she spoke to her family on her mobile phone.
Her body was found less than 12 hours later in the sea by a water biker.
Police are DNA testing backpackers on the island
Her friend, Ruth Adams, told police Miss Horton received a call from her relatives on her phone while sitting on the beach near the resort where they were staying.
While her friend strolled along the beach talking to her family, Miss Adams returned to their bungalow and fell asleep.
When she woke up she realised Miss Horton was missing.
Detectives are now trying to establish exactly what happened between the phone call and her body being discovered.
Miss Horton's father, Ian, arrived in Thailand on Wednesday after travelling from south Wales. He will be joined by one of his sons who travelled from his home in Australia.
South Wales Police said a family liaison officer flew out to Thailand with Mr Horton but would not be involved in the investigation.
Miss Horton's body is expected to be released to her family over the next few days.
Meanwhile, Michael and Jenny Adams from Bromley in Kent, whose daughter Ruth was on holiday with Miss Horton, said their "hearts go out to Kath's family in the loss, in such tragic circumstances, of their precious daughter".
"We cannot understand how, in a place of peace and beauty, such a promising life could so tragically end."