Judith Middleton, a spokeswoman for missing British yachtsman Sean Terry's family, said Mr Pokorny had told police his sole crewmate had jumped off the boat in a fit of anger.
But she told The Independent there were details in his story that did not "add up."
A man has been arrested in connection with the disappearance of a British yachtsman who vanished in the middle of the Indian Ocean.
Sean Terry, 48, went missing while piloting his boat from the paradise islands of the Maldives to Madagascar during a round-the-world sailing trip.
He was last heard from on June 18, his family said.
A week later his 40ft yacht Finnegan was piloted into the island of Coetivy off the coast of the Seychelles by Stefan Pokorny, an Austrian scuba diving instructor who had joined Mr Terry on board, they said.
Mr Pokorny has been arrested in connection with the disappearance and is due to appear in court in the Seychelles later this week.