The mysterious disappearance of an Australian family linked to an internet cult has taken a dramatic twist, with police investigating whether they were on a plane which crashed in Brazil four years ago.

It is understood WA detectives have been investigating whether the group could have travelled under false identities, but are yet to find any evidence that they did.

One of Western Australia’s greatest mysteries has gained international exposure as Australian Federal Police try to re-ignite new leads into the case of missing Nannup mother Chantelle McDougall and her daughter Leela.

The woman’s partner, Simon Kadwell (an alias) has been linked to a sect based on a doomsday book called Servers of the Divine Plan, which calls on “servers” to take up their positions on Earth before the world’s imminent end and rebirth.

WA police spokeswoman Ros Weatherall said investigators continued to keep an open mind and involvement of a religious sect was being treated as speculation.

One of the four, Englishman Simon Kadwill, 45, was revealed yesterday as the author of a new age book, Servers of the Divine Plan, predicting the world was about to come to the end of a 75,000-year cycle and enter a phase of higher consciousness.

A British citizen who has gone missing with his Australian partner, their six-year-old daughter and a 40-year-old housemate may be more of a “conman than a cult leader”, according to a West Australian cult expert.

One of four people who vanished from the south west town of Nannup nine months ago is the author of a book predicting the end of the world, the book’s publisher says.

A doomsday sect, which urges its followers to prepare for the world’s imminent end and rebirth, has been linked to the disappearance of four people from the town of Nannup, Australia, nearly nine months ago.