Eighty mentally ill US prisoners have died since 2003
More than 80 people with mental health problems have died as a result of abuse or neglect in US jails since 2003, a BBC Panorama investigation has found.
The figures follow analysis of government databases, news archives and legal investigations.
More than one million people with mental health problems are in US jails.
The US Department of Justice is investigating allegations of abuse and neglect of inmates at a number of facilities.
In facilities in six US states, BBC Panorama catalogued cases where prisoners had been beaten, sprayed with chemicals or tied down for long periods, and others where inmates had been held indefinitely in solitary confinement.
In most of the cases of death and abuse it found, the mistreatment had been initially denied, sanctioned or covered up.
Joshua Messier, 23, of Boston, who had schizophrenia, died in 2009 after four guards tried to strap him down to a restraint bed, doubling him over and compressing his chest.
The altercation began when they tried to stop him roaming the prison unescorted after a visit from his mother. The prison authorities said he had lashed out at the guards. Mr Messier's injuries included a brain bleed.
The corrections commissioner at the time said the officers' actions at the jail, in Bridgewater Massachusetts, had been "professional and appropriate".
The authorities now accept the officers should not have compressed Joshua's back and say they have improved staff training.
Five years on, none of the officers has faced prosecution - but they have recently been put on leave pending further investigations.
Mr Messier's mother, Lisa Brown, said: "I swear this world's gone mad. Nobody seems to care about anybody, especially a person with mental illness.
"Nothing's been done, nobody's been prosecuted. And I heard some of them, their punishment was they had some time off, paid time off, they got a vacation for killing my son."
With a severe shortage of mental healthcare in America, corrections facilities are overwhelmed by massive numbers of inmates with mental health problems.
Paul Schlosser, 32, a former army medic convicted of armed robbery, has bipolar disorder.
He made deep gashes in his arm while being held in segregation for two months at the Maine Correctional Centre in Wyndham in 2012.
He said the medicine he was prescribed was not working and begged for more.
He kept pulling the bandages off his wounds and demanding medication, so staff moved him - saying later it was to get him treatment. They put him in a restraint chair, strapping down his arms, legs and head. He then spat at an officer.
They sprayed a highly potent pepper spray into his face from inches away. The manufacturers say it should only be used at a minimum distance of 6ft (1.8m).
"I started panicking - you're immobilised so you have no way to kind of cover your face. It's just very claustrophobic, not being able to breathe and being strapped in," he said.
"It burns your ears, it burns any sensitive areas on your body. It definitely seemed like I was tortured."
Maine's Department of Corrections declined to comment on the incident, but said the captain in charge still worked as a corrections officer with direct contact with inmates.
Panorama was given access to Cook County Jail in Chicago, now inadvertently also acting as one of the biggest mental institutions in the country. It is home to 10,000 inmates, including 3,000 who are mentally ill.
"It's just abundantly clear that we have criminalised mental illness," said sheriff Tom Dart, who runs the jail.
Starting in the 1950s the US shut down its network of mental asylums amid complaints of rampant abuse. The plan was to replace them with a more humane system of community care. But funding has been limited, and jails and prisons are ill-equipped to deal with vast numbers of the mentally ill.
"There's no question that the jails and prisons are worse than the old mental asylums," said Dr Fuller Torrey, one of America's leading psychiatrists.
"The mental asylums were unpleasant, but not nearly as stressful as the jails and prisons are for people with severe mental illness. Now we've definitely gone backwards in time," he said.
With mental-health care budgets being cut further in many parts of the country, there are now 10 times more mentally ill Americans in jails and prisons than state mental-health institutions.
Paolo del Vecchio, who leads the federal mental health programmes, admitted that half of Americans with mental health problems did not receive the services they needed.
"We need to do a much better job and have the will and the desire frankly to increase the community capacity to provide services," he said.
Most Americans think of widespread brutality against the mentally ill as a just a shame of the past, but it is not.
"In terms of the history of 20th Century America, our failure to treat people with severe mental illnesses and the consequences is really one of the great social disasters of the century, and I think it will be regarded in retrospect as something we'll be very ashamed of," said Dr Torrey.
Panorama: Bedlam Behind Bars on BBC One, 7 July at 20:30 BST.