A MYSTERIOUS letter written just before Swedish backpacker Max Castor disappeared is the only clue to what may have happened to him.

The 20-year-old was on the trip of a lifetime travelling through Australia with two friends when he went missing in 2005.

“Something strange has happened to me and I don’t know how to cope with it ... I am vanishing ... no tears,” Max wrote in a letter to his brother before posting it home with his belongings and return plane ticket, closing his bank account and disappearing.

In the letter, written in English rather than Swedish, Max said goodbye to his family.

He was last seen at the local store in Wye River, Victoria. He told the shopkeeper he was heading north. There was another possible sighting shortly after in Cowra, NSW.

His father, Ron Castor, speaking from Stockholm, said the years he had spent without his son had been like living with ‘a wet blanket’ thrown over him.

Mr Castor believes Max is still alive and possibly living on the Far North Coast.

“His friends guess he is somewhere in your area,” MrCastor said.

“Max’s friends and fellow travellers said he was attracted to the easygoing lifestyle there. They passed the place during their trip.”

There was also a reported sighting of a Swedish man who looked like Max in a local restaurant.

“He was interested about Sweden, but kept very silent about himself,” Mr Castor said.

Mr Castor continues his search by asking Swedes travelling to Australia to look out for Max.

Over the years more than 100 possible sightings of his son have been reported.

Anyone who has seen Max should contact the National Missing Persons Unit on 1800 000 634 or Crime Stoppers on 1800 333 000.

His family has posted a $5000 reward for useful information about his disappearance, available through the International Rewards Centre.

For more information visit www.internationalrewardscentre.com.