Really interesting article about him, thanks for sharing. Apparently he was an actor, painter, and three-time prison escapee with multiple aliases.

The Guardian article mentions some more stuff about his past:

[Filmmaker Heath Davis] and authors including Mark Dapin had already uncovered stories of Karlson’s prison escapes that are said to include picking the lock cuffing him to a sleeping officer and leaping from a moving train and swimming off a prison island before being rescued by a benevolent fisher.

[...]

“He was some sort of trained actor, he learned that in prison, but he was also a natural showman,” Watt said. “He bluffed his way out of a court in Sydney, said he was a detective, and to do that he must have been a very confident showman … and a bit of a conman as well”.