The BNZ says a synthetic DNA spray was the key to convicting a man who used a bomb hoax to rob a branch of the bank in South Auckland.
Clive McKay, 47, of Tuakau held up the BNZ Manukau branch in February and left what he claimed was an explosive device, threatening to detonate it remotely.
On Wednesday he was sentenced to more than six years in prison.
Bank spokesperson Owen Loeffellechner said police were able to prove McKay was the offender because an automatic system sprayed him with synthetic DNA.
Mr Loeffellechner says the bank hopes the case will discourage other would-be bank robbers.