Dunn associated with the known bushrangers
Ben Hall and
John Gilbert. Dunn joined the
Hall gang in October 1864, a welcomed new member after police captured gang members Dunleavy and Mount. In late 1864, during the robbery of a mail coach near
Jugiong, Gilbert shot and killed Sergeant Parry. On 26 January 1865, Hall, Gilbert and Dunn were at
Collector, near
Lake George. While Hall and Gilbert were holding up the hotel, Dunn shot and killed the local police officer. Dunn twice fired, his first shot hitting once in the face and the second that pierced the heart. Constable Samuel Nelson was the sole policeman in the township and the father of eight. Dunn also shot at Nelson's son but missed. In May, Hall, Gilbert, and Dunn were proclaimed outlaws; the passing into law the
Felons Apprehension Act 1865, which allowed known bushrangers to be shot and killed rather than taken to trial, this put them outside the law and liable to be killed by anyone. Hall had separated from the other two and later was surrounded by police in the bush near
Forbes, New South Wales, and shot dead. Gibert and Dunn on hearing the news of Hall's death headed for Dunn's grandfather's property at Murrumburrah. == Gilbert's capture and death==