In the Auckland Supreme Court, Dennis Gunn was convicted of the murder of a postmaster and sentenced to death. In what was claimed to be a world first for a capital crime, the conviction was based almost entirely on fingerprint evidence.
On Saturday 13 March 1920 Augustus Braithwaite, the postmaster at Ponsonby, was murdered in his own house. His keys were taken and the Post Office strongroom was opened and ransacked. Fingerprints found on three cash boxes were sent to the Criminal Registration Branch (CRB) at Police Headquarters in Wellington for analysis.
That Monday a former prison warder named Hughes told the police he had seen Dennis Gunn hanging around the Post Office. Hughes recognised Gunn from an encounter in 1918 when the latter had been sentenced to two weeks’ imprisonment for failing to enrol for military service. His fingerprints had been taken at the time.
The names of Gunn and another suspect were sent by telegram to the CRB. By Tuesday 16th the fingerprints on the cash boxes had been matched with Gunn’s fingerprint form. He was arrested the next day and charged with murder and burglary. Property stolen during the robbery, including Braithwaite’s keys and a recently fired pistol, were found in a gully near the house in which Gunn lived with his mother. Grooves on the weapon corresponded with marks on the two bullets found in Braithwaite’s body. A fingerprint on the weapon was matched with Gunn’s.
Gunn’s lawyer argued that the fingerprint evidence was inconclusive. While admitting to a role in the robbery, Gunn claimed that Braithwaite had been killed by a man known as Alfred or Bonny O’Meara. The jury was not convinced. After a five-day trial Gunn was convicted and sentenced to death on 28 May 1920. He was hanged in Auckland on 22 June.