Anonymous letter gives major new clue in what happened to Peter Falconio's body.

It’s the Australian crime no one has ever been able to forget: British backpackers Joanne Lees and her boyfriend Peter Falconio were travelling around Australia when they were kidnapped by Bradley John Murdoch.

After five hours hiding from her attackers, Lees managed to escape. But Peter Falconio was murdered.

Despite his killer being brought to justice in 2005, the 28-year-old's body has never been found, and Murdoch has never disclosed where it was.

Now, the author of an anonymous letter sent to NT News claims to know the whereabouts of the British backpacker's remains.

The letter, which was provided to Northern Territory police after it was sent to the publication, claims Falconio's body is buried in remote Western Australia.

"Murdoch had cut the body up and put it in two large...bags that were watertight and smell proof," the typed one-page A4 letter read.

"He told [a criminal associate] to go straight back to Perth and dissolve the body parts in acid and put what was left in the Swan River.

"[The associate] told me he went way past Geraldton and buried both the bags unopened in a nice spot and even made up a cross. Later he realised who he had buried and was in a bad way about it."

The author of the mysterious note claims he formerly had ties to the associate in the letter - whose identity has not been released to the public - but lost touch with him after being told about his role in Falconio's murder.

"I feel the Falconio family and his girlfriend [Joanne Lees] deserve to know what happened to their loved one," the author of the note added.

The revelations come just two months after Lees returned to the Australian Outback in an attempt to find her former boyfriend's remains.

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"I love Pete so much and I want to bring him home and I need to bring him home," she told 60 Minutes at the time.

"The important thing is for me to come here and at least try [and find him]."

The Northern Territory police has confirmed they are investigating the note.

"[We] are reviewing the contents of the letter to determine whether it contains material which should be investigated further," they confirmed in a statement to NT News.

The police also confirmed they receive "dozens" of letters each year from people claiming to know details of Falconio's murder, but this particular letter had "piqued their interest".