Since its launch, the military-led operation that is Operation Sovereign Borders has been conducted covertly, with little justification, and we are told this is necessary.

But what actually happens under the banner of this secretive operation? What kinds of things do Australian officials do to get boats to turn around? And what if, under the veil of secrecy, the line between the people smugglers and the government starts to blur? What if, on the vast open seas, Australian officials begin to direct and even participate in criminal and abusive acts?

These questions are no longer far-fetched. These are questions we at Amnesty International were forced to ask ourselves after allegations surfaced in 2015 that Australia had paid off people smugglers to return asylum seekers to Indonesia.

We began an investigation, looking at seven turnbacks conducted between late 2013 and mid-2015. The findings were published in October 2015 in a report entitled: By Hook or by Crook: Australia’s Abuse of Asylum Seekers at Sea.

Our investigation of the May 2015 incident was based on interviews with all the adult asylum seekers on board, the boat crew and Indonesian police, backed up by photo and video footage.

The evidence indicates that Australian officials intercepted and boarded a boat en route to New Zealand and then detained the bulk of the passengers in prison-like cells on board a Border Force ship for a week at sea. Despite claims by government officials, testimony gathered by Amnesty International suggests the boat was not in distress and did not request assistance from the Australians. Indeed, I spoke to one of the asylum seekers about this just a couple of days ago, and he was emphatic that no distress call was made.

During the turnback incident, we received reports that Australian officials subjected these people seeking asylum to various forms of ill treatment. These allegations included: forcing the adult male passengers to stay outside on the boat overnight in heavy rain without protection from the elements, and confiscating medicines from the passengers and denying them access to medical assistance when they requested it.

In earlier turnback incidents, we received even more disturbing allegations of physical violence and verbal abuse, such as the use of pepper spray on asylum seekers and people jumping overboard when confronted with Australian officials due to panic and fear.

Then there is the alleged payoff made in May 2015. Our evidence corroborates what has been widely reported in the media, that Australian officials working under Operation Sovereign Borders paid US$32,000 to six crew members to smuggle people originally bound for New Zealand back to Indonesia instead. The Australians provided maps showing the crew where to land in Indonesia, a GPS device and gave them the boats to sail.

Witness testimony backed by video footage reveals how the intervention by Australian officials endangered the lives of the people in that turnback by transferring them to boats that did not have enough fuel.

Applying a secretive and militarised approach to managing the treatment of vulnerable people is a recipe for disaster

We also spoke to other asylum seekers who were deeply suspicious Australian officials had paid off their boat crew when they were pushed back to Indonesia in July 2015. This allegation warrants investigation too.

In none of the turnbacks we investigated did asylum seekers tell us they were asked by Australian officials about their claims. It appears they were each collectively expelled without regard for the risks they might face if pushed back.

It certainly wouldn’t be surprising to many that Amnesty International has grave misgivings about Operation Sovereign Borders. Applying a secretive and militarised approach to managing Australia’s treatment of vulnerable people is a recipe for disaster.

This investigation has only reinforced our concerns: paying off boat crews, illegally detaining vulnerable people at sea, subjecting them to ill treatment and then pushing them back to an uncertain fate is abhorrent practice for any government – and evidence of these practices cannot be swept aside.

Open government and freedom of the press are cornerstones of a healthy, human rights protecting society. When government officials tell us that we don’t need to know, we should be wary. When ministers deny wrongdoing, but fail to produce the facts, we should be deeply sceptical.

But the truth is, when it comes to Operation Sovereign Borders, we have become complacent. It has been too easy to look away and allow the strong arm of the Australian government to keep the global refugee crisis out of sight and out of mind.

And in that vacuum of public accountability, the government has gone too far. This is the way of countless governments Amnesty International encounters – but it is not what I expect from my home country.

Perhaps if there was a little more accountability we could come together as a nation to do the right thing and help people seeking our protection, not push them away.

The ball is now in Malcolm Turnbull’s court. I can only hope he will come to show the moral leadership his predecessors did not.

Steph Cousins is Amnesty International Australia’s government relations manager. She will be joining Amnesty’s national refugee coordinator Dr Graham Thom to give evidence to the Senate legal and constitutional affairs committee inquiring into the boat payment scandal at hearings on Friday