Since the death in captivity of the last known thylacine in 1936, there's been endless speculation that a small population of the animals may have survived.
One of the true believers is Col Bailey.
Describing himself as a bit of an old bushie, Col has spent much of the last 45 years scouring Tasmania for signs of the thylacine.
In his new book Shadow of the Thylacine - One Man's Epic Search for the Tasmanian Tiger, he documents this search and reveals a personal encounter with what he believes was a Thylacine in 1995.