Police say Bates got into an argument with two men around 2 a.m. Friday outside the Da Vinci Villa Hotel in the Russian Hill neighborhood.
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He was pronounced dead at a hospital. Two men were detained for questioning. Police say no weapons were involved in the fight.
Bate lived in Woolner, a suburb of Darwin. He was an analytical chemist with SGS Australia, which offers a range of testing and certification services to businesses.
Australia's Department of Foreign Affairs and Trade said it was providing Bate's family with consular assistance.
SFPD says they will not be releasing more details about the suspect until Monday.