By the time guards pulled his lifeless body from the locked shower stall, scalding water had burned Darren Rainey so badly that his skin sloughed off his body. A 50-year-old mentally ill inmate at South Florida’s Dade Correctional Institution, Rainey was allegedly locked in the showers for an hour as punishment, after he irked guards by defecating on the floor of his cell and refusing to clean up the mess.

"I can’t take it no more. I’m sorry! I won’t do it again!" his fellow inmates said they heard him scream repeatedly before he died.

No one heeded his cries.

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The story of Darren Rainey’s death is so horrific, it sounds like a nightmare that could have only come from an episode of HBO’s bloody, torture-centric show Game of Thrones.

But Rainey’s end was no aberration—it was the third grisly death of a mentally ill inmate to come to light in just the past month. Last week, New York City's main jail complex, Rikers Island, received international scrutiny over the death of 39-year-old schizophrenic inmate Bradley Ballard, who was found lifeless, covered in feces, with his genitals mutilated, in his solitary confinement cell after being denied medication for seven days.

Rikers was already under fire for the February death of 56-year-old Jerome Murdough, a Marine veteran who suffered from bipolar disorder and was found to have died of hyperthermia: Essentially, he was baked to death in his cell after temperatures topped 100 degrees because of malfunctioning heating. Mentally ill patients who, like Murdough, take psychotropic medicines are particularly vulnerable to shoddy climate controls in prisons because the drugs can impair the body's ability to cool itself by sweating.

Though abuse or negligence on the part of correctional officers is suspected in the deaths of at least two of these inmates, advocates suggest that these deaths have brought a far larger issue to light: the criminalization of mental illness.

According to the National Institute of Mental Health, more than 64 percent of inmates in America’s jail systems suffer from mental illness, and 56 percent of inmates in state prisons are mentally ill. Though many are legitimate criminals and potential dangers to society, others are simply incarcerated on petty crimes because they have nowhere else to go, and no one is helping them get treatment.

“Jails have become America’s de facto mental health institutions,” said Katrina Gay, communications director for the National Alliance on Mental Illness, a nonprofit advocacy group.

“We have 108,000 psych hospital beds open at any given time in America. But we have more than five times that amount of mentally ill people in jails or homeless shelters on any given night," Gay said.

What lands mentally ill people behind bars typically doesn't amount to more than misbehavior—acting strangely in public places or unwittingly committing minor crimes such as vandalism or shoplifting. When that happens, the quick answer for concerned bystanders is to call 911, which introduces the mentally ill to the criminal justice system instead of the help they need.

"Jail is among the array of downstream negative consequences for people not getting treatment they need for a serious medical condition,” said Gay.

Jails are simply not set up to handle this population.

For example, in Massachusetts' correctional systems, guards received an average of two hours of training, annually, in how to deal with the mentally ill, according to Bradley Brockmann, executive director of The Center for Prisoner Health and Human Rights at Brown University Medical School.

The results speak for themselves.

“Being in jail is about following orders,” said Brockmann. “Stand up, sit down, put your hands behind your back. Mentally ill people have great difficulty following orders—it’s often why they wound up in jail in the first place."

Even inmates with ADHD struggle to follow more than two orders in a row, and "that can result in penalties, loss of privileges, or isolation," Brockmann said.

Any of those punishments can render the mentally ill a danger to themselves or to guards.

The immediate solution is finding treatment for the mentally ill before they wind up in jail on petty offenses, Brockmann said.

“The key to this problem is treatment in the community,” said Brockmann. “Until we have a comprehensive mental health policy in this country, we will have a disproportionate amount of mentally ill people in correctional facilities.”

By ignoring mental health on the streets, America has forced its jailers to become the nation’s primary mental health providers—something they have no training in and no business doing. As long as this remains the status quo, we’ll likely be hearing more stories like Rainey’s.