In a letter to U.S. Attorney General Loretta Lynch, 37 civil rights, human rights and church groups on Monday asked the U.S. Department of Justice to investigate "harrowing allegations of abuse and torture" of prisoners at the federal prison at Lewisburg, Pa., based on stories last month by NPR and The Marshall Project.

Groups signing the letter included the American Civil Liberties Union, Human Rights Watch, National Alliance on Mental Illness and Southern Poverty Law Center.

"Reported conditions at USP Lewisburg call for swift intervention and accountability," said the Rev. Laura Markle Downton, of the National Religious Campaign Against Torture, one of the drafters of the letter.

The letter writers said the stories showed "a facility in crisis that requires greater oversight, transparency and accountability to ensure humane and lawful conditions of confinement."

The investigation by NPR and The Marshall Project found violence between prisoners is six times more likely at Lewisburg, compared with all federal prisons. That violence is more likely because of the practice of putting dangerous men together in one solitary confinement cell — a practice called double celling — for 23 to 24 hours a day, plus a lack of mental health care and the frequent use of restraints for prisoners who refuse to live with a specific cellmate. One man in our investigation, Sebastian Richardson, was put in restraints for 28 days after he refused to cell with a man who had a reputation in the prison for attacking his cellmates.

Documents obtained by NPR and The Marshall Project showed that inmate-on-inmate attacks are a near daily occurrence and that at least four men have been attacked and killed by their cellmates since 2009. The prison in Lewisburg houses a Special Management Unit for about 1,000 prisoners who are considered disruptive or dangerous and were removed from other federal prisons.

"We believe it took the NPR/Marshall Project reports to show people how terrible the practice of double celling and use of hard restraints really is," said Dave Sprout with the Lewisburg Prison Project, a group that advocates for prisoners there and has been asking for an investigation since 2009.

The groups signing the letter want Lynch to ask Michael Horowitz, the department's inspector general, to investigate. The federal Bureau of Prisons, which manages the prison at Lewisburg, is part of the Justice Department.

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