On Wednesday, Australia learned the result of a national vote that showed decisive support for legalising same-sex marriage. The discussion over changing the law has been one of the most hotly debated issues in the nation’s recent social and political history.

But the death of a university lecturer in Adelaide 45 years ago led to an even more fundamental change for Australia’s gay community. Jamie Duncan reports.

In the foyer of the University of Adelaide’s law faculty building, a photograph of a sober-looking man wearing dark-rimmed glasses stares out at posters backing a “yes” vote on Australia’s same-sex marriage postal survey.

The scene is a symbol of evolving social debate in Australia.

The photograph is part of a memorial to Dr George Duncan, a gay law lecturer at the university who in 1972 was killed a stone’s throw away at a riverbank in an attack suspected to have been committed by police officers.

The crime, still unpunished, revolted mainstream Australia and led the state of South Australia (SA) to become the first national jurisdiction to decriminalise homosexuality.