Canberra: Australia’s shocking treatment of Indigenous people has been laid bare with the publication of new figures by the Guardian showing 147 Indigenous people — some of them children — have died in custody in the past 10 years.

Opposition parties have declared it a “national shame” and Aboriginal groups have demanded the government immediately allow independent monitoring of all detention centres, with Indigenous prisoners as the priority.

Just 2.8 per cent of the Australian population identifies as Indigenous. Yet Indigenous people make up 27 per cent of the prison population, 22 per cent of deaths in prison custody, and 19 per cent of deaths in police custody.

Guardian Australia’s investigation into 10 years of deaths in custody cases found serious systemic failings:

— 407 Indigenous people have died since the end of a royal commission that outlined ways to prevent Indigenous deaths in custody, almost 30 years ago

— Indigenous people are dying in custody from treatable medical conditions, and are much less likely than non-Indigenous people to receive the care they need

— Agencies such as police watch-houses, prisons and hospitals failed to follow all of their own procedures in 34 per cent of cases where Indigenous people died, compared with 21 per cent of cases for non-Indigenous people

— Mental health or cognitive impairment was a factor in 41 per cent of all deaths in custody. But Indigenous people with a diagnosed mental health condition or cognitive impairment, such as a brain injury or fetal alcohol syndrome disorder, received the care they needed in just 53 per cent of cases

— Families waited up to three years for coronial inquest findings in some states

Greens senator Rachel Siewert said: “Guardian Australia’s ‘Deaths Inside’ database released today is an incredibly important initiative that shines a light on this devastating issue.”

Pat Dodson, a Labor Senator and Indigenous man from Western Australia, said. “We are going backwards as a nation. The current government is failing to show leadership and commitment to turning around the appalling state of how our justice system treats Indigenous people.”

However, the numbers tell only part of the story. Reading 463 coronial reports, Guardian Australia found a record of systemic failure.

An Aboriginal woman with a chronic injury and a tooth abscess was denied pain medication for six weeks after being transferred to Townsville women’s prison in 2010. Her medical records had not arrived with her and, apart from issuing Panadol, authorities did not believe she was in need of pain relief. Six weeks after transfer, she took her own life. The coroner said the pain was “a contributing factor in her despair” during her final weeks.

“It simply cannot be that difficult to give people in custody medical attention. How can people in 2018 be dying in prison from a tooth abscess?” Siewert said.

An Aboriginal man in the grip of cardiac arrest was made to walk to a guard station to use a portable oxygen unit before an ambulance was called.

Another Aboriginal man died of heart disease lying on a concrete bench in a Darwin police watch-house cell. The coroner said “a sick middle-aged Aboriginal man was treated like a criminal and incarcerated like a criminal; he died in a police cell which was built to house criminals ... In my view, he was entitled to die as a free man.”

Prisoners known to be at risk of self-harm were held in cells with hanging points, or placed in cells alone.

Research by the Guardian found that families of those who die also experienced poor treatment. Coroners have criticised unnecessary delays in notifying next of kin. In one case, a father found out his son had died when another prisoner called him several hours after the death, long before police notified him officially.

Related: We examined every Indigenous death in custody since 2008. This is why

An inquest is currently underway in South Australia into the death of Wayne Morrison, who died in hospital three days after an altercation with corrections staff at an Adelaide prison left him braindead.

Footage made public on Monday showed the incident leading up to Morrison’s transfer in the prison van. At one stage, more than 16 officers crowd the hallway where Morrison is being restrained, facedown. It is almost impossible to see him beneath them.

Once restrained, he was carried outside and placed facedown in the rear of a prison escort van to transfer him into the prison. Eight prison staff, including the driver of the escort vehicle, accompanied Morrison on the journey in the van.

There is no footage of what happened inside the van, but counsel assisting the coroner, Anthony Crocker, told the court that “when the van arrived at G Division, Morrison was found to be blue and unresponsive”. The journey took a little under three minutes.

“Precisely what occurred in the van is unknown as seven of the eight prison staff who accompanied Mr Morrison on the journey have declined to provide police with statements,” Crocker said.

His family told Guardian Australia they did not receive a formal notification that he had been injured and were denied entry to the hospital for more than 10 hours.