A British coroner has described as "mediaeval" some aspects of the Thai police investigation into the death of a UK man after a full-moon party on Koh Phangan earlier this year.
Sussex coroner Alan Craze made the comment at the inquest this week into the death of Andrew Apperley, whose body was found in the sea nine days after he was last seen on the southern tourist island in February.
The local investigating officer, Pol Capt Suteep Chadakan, had given the cause of death as asphyxiation by drowning. But Mr Craze said the cause could not be definitively ascertained because of the poor information provided to him.
At the hearing in Eastbourne, he said the toxicology report carried out by Thai authorities was "mediaeval", the BBC reported.
Because of the extent to which the body had decomposed by the time British pathologists could carry out their own examination, they were unable to find a clear cause of death, the court heard.
In a statement read out at the inquest, Pol Capt Suteep said a post-mortem examination found no signs of trauma or external wounds consistent with a struggle. The statement said the death was "not murder but unnatural".
The statement said Apperley, 38, "was drinking and taking other substances and became delusional" during the party, and "walked into the sea where rocks extended out into deep water and drowned".
However, the family previously told the BBC they were pressing Thai authorities to investigate further because they suspected foul play. They had found text messages on his phone, suggesting he felt in danger, they said.
Apperley, an Eastbourne resident who was married and had a seven-year-old daughter, was staying in a hotel on Koh Samui and took a boat to the party on Koh Phangan on Feb 12. He sent a text to his mother saying he intended to return to Samui the following day. His hotel on Phangan reported him missing four days later.
"We didn't get closure. We will probably never know what happened to Andrew," his wife Magdalena Apperley told The Independent after the inquest. "We can't rule out foul play, we can't rule out drugs, or anything else that could have happened.
"The damage is done. We really hope his death can be turned into something positive and serve as a warning to other tourists going to the parties to be careful."
Unexplained tourist deaths are not uncommon in Thailand, which welcomed more than 32 million foreign visitors last year. The number and nature of the cases has even inspired the creation of a website, Farang-deaths.com, devoted exclusively to the subject.
The coroner in the Apperley case said there was a lack of evidence from the Thai authorities, who had not carried out a toxicology report.
"There's pretty much no control on the island. Police presence there will have been hit and miss," The Independent quoted him as saying.
"I'm not being rude about the Thai authorities, I have been there many times, I love the country. But in terms of my job as a coroner it's hit and miss as to whether I will get useful information or not.
"I'm not getting sufficient or sufficiently reliable information. I think it's down to resources."