Ned Kelly, the infamous Australian bush ranger, may finally be able to rest in peace after a skull believed to belong to the outlaw was handed to authorities for forensic testing.

Kelly's skull has been missing ever since it was stolen from a display cabinet at the Old Melbourne Gaol in 1978, just yards from where Kelly was hanged in 1880 for killing a policeman. The crime went unsolved and the whereabouts of the skull became one of Australia's greatest mysteries.

Then, earlier this week on the 129th anniversary of Kelly's hanging, Tom Baxter, a farmer from Western Australia, delivered a skull to the Victorian Institute of Forensic Medicine, claiming it was the same one that was stolen from the jail more than 30 years ago.

Mr Baxter returned the skull after years of negotiations with Heritage Victoria. He has refused to say if he was involved in the original theft and how he came across the skull, which has been in his possession for decades.

Rob Hulls, Victoria's attorney general, said exhaustive tests would be conducted on the skull to determine if it was authentic.