Tasmanian backpacker Rye Hunt died from either dehydration or from drowning as he swam from a small island near Copacabana beach, Brazilian police say.

Police confirmed on Monday that a body found washed up near Rio de Janeiro last week was missing Australian backpacker Rye Hunt but due to the advanced stage of decomposition they were unable to determine a cause of death.

Forensic investigators now say the 25-year-old died during the 800-metre swim from the island of Cotunduba off Copacabana Beach.

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Rio police investigator Elen Souto said the circumstances in which the body was found suggested Mr Hunt died during a psychotic episode.

“According to our investigation … the location of the body supports the investigation that Rye went to the island of Cotunduba during a psychotic episode, coherent with the state of someone who is running away from a danger created in their minds,” she said.

“Certainly because of his physical debilitation, probably because of dehydration, he must have tried to leave the island and not have had enough strength or health to get to land.”

Rye Hunt (left) was on a global adventure with travelling mate Mitch Sheppard when he went missing in Rio. Photo: Facebook

Police had said they believed Mr Hunt disappeared after suffering drug-induced psychosis.

Brazilian newspaper O Globo is now reporting police said Mr Hunt had drugs with him when he arrived in Rio from Argentina.

Journalist Gabriel Rosadamata said it was unclear if police would investigate how the drugs were taken into Rio.

“Police didn’t give a lot of details so we are still, there are some aspects of this case that are still a mystery to us in Rio,” she said.

Mr Hunt’s family confirmed yesterday that the body had been released to them, and said they were appealing to Foreign Minister Julie Bishop for assisting in bringing his ashes home to Tasmania.

Ms Souto said Mr Hunt’s body had been identified using dental records.

“The body was released after identification,” Ms Souto said.

“The family plans on cremating Rye here in Brazil, and [then taking] his ashes to Australia.

“The cremation has not yet happened but the body has been released, they are just waiting for judicial clearance for the cremation.”