A timber cross memorial to the 35 people killed in the 1996 Port Arthur massacre (Image: AAP/Robyn Grace)

As soon as Australia found out about the horrors committed at Port Arthur in 1996, whispers started that something was amiss about the official account of how Martin Bryant killed 35 people.

These conspiracy theories that someone else was responsible or helped carry out the massacre are patently untrue.

Bryant, who was known for killing animals and riddling their bodies with bullets, was the one who fired indiscriminately into a cafe, gift shop, a car and a bus at point blank range with an AR-15. There is no credible evidence that suggests otherwise.

While just one in 10 Australians believe that the Port Arthur shooting was orchestrated to restrict gun laws according to recent research, tens of thousands of Australians have come together in online groups dedicated to disbelieving what happened. The conspiracy theory has found new life in other conspiracy and extreme online communities.

Sanitised versions of these theories, couched as questions, have even made their way into the mouths of elected officials and are cited as reasons to push back against Australia’s strong gun laws.

New home on social media

Like with many other pre-internet conspiracy theories, Port Arthur “truthers” have found a new home on social media platforms.

There are multiple active Facebook groups with thousands of members who continue to doubt what happened on April 28, 1996.

These range from groups who call for an inquiry into what happened to those who outright believe that the event was a “false flag” event carried out by some third party.

Most of these groups have been created in the past few years and often see big spikes in growth around the anniversary of the mass shooting.

One group, with more than 10,000 members, has added more than 600 in the last week.

On YouTube, there are dozens of videos that claim to offer different accounts of the massacre with thousands of views.

A 2014 video of an interview with a retired Victorian police officer who names third parties as responsible for the shooting has more than 110,000 views. The video’s comments section is filled with recent comments discussing the video.

Alt-tech website Bitchute — a video platform loved by Neo-Nazis and conspiracy theorists for its non-existent moderation — is also filled with Port Arthur denialist videos.

Port Arthur denialism making headways

This conspiracy theory has been finding new audiences in other conspiracy communities, facilitated by shared mistrust of the government and a desire to see alternative explanations for mainstream events.

Popular Australian QAnon believers, anti-vaxxers and anti-fluoride Facebook pages have all dabbled in Port Arthur denialist content.

It’s not just conspiracy communities, either. Posts and memes questioning the massacre are finding their way into far-right online spaces.

Popular Facebook groups and pages with tens of thousands of followers — such as Stand Up For Australia – Melbourne, Drain the Swamp Australia, and A Different View — which deal in culture war and anti-left content (often straying into xenophobia, racism and sexism) have all posted content that questions whether the shooting was a set-up.

One type of space that has been ripe for this kind of content has been online shooting communities.

Bristling with frustration over the resulting gun reforms implemented by Howard just days after the shootings, communities such as Gun Owners of Australia (10,800 members) and Australian Gun Rights are rife with people who are skeptical or full-blown denialists.

In these groups, the denialism serves a purpose: the official narrative of what happened in Port Arthur was used to justify laws that they consider draconian. Casting doubt on the mass shooting undermines the justification for these restrictions.

While some members of groups push back, discussions of Port Arthur in these largely grounded, rational groups quickly descends into outright conspiracy.

Public figures lend credence

Most mainstream political figures are unequivocal about the mass shooting. The subsequent reforms have remained largely sacrosanct in Australian political culture. Even Australian conservative politicians have for the most part remained committed to gun control compared with their US counterparts.

But there are some who have stoked conspiracy claims. One Nation’s Pauline Hanson — no stranger to conspiracy — was famously caught on secret camera doubting what happened at Port Arthur.

“Haven’t you heard that? Have a look at it. It was said on the floor of Parliament. I’ve read a lot and I have read the book on it, Port Arthur. A lot of questions there,” she said.

Another One Nation state candidate similarly posited that the whole shooting was “fabricated”.

Former Liberal Democrats senator David Leyonhjelm has repeatedly called for an inquiry into the massacre during his term in Parliament.

Even this week, the gun rights advocate doubled down on his questions. “It’s time we had answers. The victims deserve it,” he tweeted.