An investigation into the death of a British tourist in Thailand has been branded "medieval" by a coroner.
Sussex coroner Alan Craze made the criticism at the inquest into the death of Andrew Apperley, whose body was found on the island of Koh Phangan.
Thai investigating officer Suteep Chadakan had given Mr Apperley's cause of death as asphyxiation by drowning.
But Mr Craze said the cause of death was unascertained because of poor information provided to him.
Mr Apperley was reported missing after failing to return to his hotel following a Full Moon party in February. His body was found four days later.
At the hearing in Eastbourne, Mr Craze also said a toxicology report carried out by the Thai authorities was "medieval".
Because of the extent 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 by Mr Craze, police captain Chadakan said a post-mortem examination found no signs of trauma or external wound consistent with a struggle.
He said 38-year-old Mr Apperley "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 the Thai authorities to investigate further because they suspected foul play.
They had found text messages on his phone dating from 13 February, suggesting he felt in danger, they said.
Mr Apperley, who was raised in Gloucestershire and had a young daughter, was staying in a hotel on the island of Koh Samui, from there he headed by boat for the party on Koh Phangan.
Mr Craze recorded an open conclusion on the cause of his death.