The body of backpacker Rye Hunt was so decomposed that a cause of death could not be fully determined, says the detective leading the investigation in Brazil.
The remains of the 25-year-old are expected to be cremated and returned to Australia from Rio de Janeiro as early as Wednesday.
Mr Hunt went missing on May 21 after becoming separated from his travelling companion Mitchell Sheppard at the Rio airport.
They had an argument after the two took what is suspected to be a highly potent hallucinogen known as NBOMe.
A body that washed ashore at Marica near Rio on June 8 has been identified as Mr Hunt from dental records and the remains released to his family, Detective Elen Souto said on Tuesday.
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"We were told by the police station in Marica that a dead body, with clothing similar to what Rye was wearing when he went missing, had been found," the detective said.
"The head, arms and legs were in a skeletal state."
The investigation has been completed without the cause of death being fully understood, she said.
Local residents found the body covered in sand on the idyllic Guaratiba beach in the district of Marica, 50km from the centre of Rio.
Mr Hunt was last seen by a fisherman on May 22 on the island of Cotunduba, near Copacabana beach in Rio, where he had apparently swum.
According to the testimony of the fisherman, he was acting "high", Detective Souto said.
He gave him water but Rye did not request help, she said.
"He drank the water quickly, stared at the boat, then looked away to the horizon and was gone."
The testimony of the fisherman supports the idea that Mr Hunt died while trying to swim away from the island, probably due to physical weakness or dehydration, police said.
His remains will be cremated and his ashes scattered in his home state of Tasmania when his uncle Michael Wholohan and girlfriend Bonnie Cuthbert bring them home, which could be as early as Wednesday pending the approval of a Rio court.
