The two Mawbey girls who were murdered by Jimmy Governor, Grace and Hilda, had their heads smashed in with an Aboriginal club called a nulla nulla. The school teacher who was boarding with the Mawbey family, Ellen Kerz, met with the same fate.
Authors of The True Story of Jimmy Blacksmith (2002), Moore and Williams, say that before the murders at Breelong, Jimmy and Joe Governor had bought two tomahawks from a trader, Sam Ellis.
One was used around the camp, and the other remained in the possession of Joe.
The tomahawk in the Police and Justice Museum in Sydney is the one used around the camp.
It has marks indicating it had been used as a hammer.