In jails and prisons throughout the United States, correctional staff have sprayed mentally disabled prisoners with painful chemicals, shocked them with electric stun weapons, and strapped them for days in restraining chairs and beds, according to a report that will be released Tuesday.

In its 127-page investigation of mostly state and local prisons, Human Rights Watch details incidents in which prison workers have used unnecessary and excessive force against prisoners with mental disabilities.

In one case in the report, “Callous and Cruel: Use of Force Against Inmates With Mental Disabilities in U.S. Jails and Prisons,” staff members at a California prison used pepper spray on a prisoner about 40 times and threw four pepper-spray grenades into his cell after the man, who claimed to be “the creator,” resisted being removed.

“Jails and prisons can be dangerous, damaging and even deadly places for men and women with mental-health problems,” said Jamie Fellner, U.S. program senior adviser at Human Rights Watch and author of the report. “Force is used against prisoners even when, because of their illness, they cannot understand or comply with staff orders.”

Fellner said that no national data is available on the scale of the problem in the nation’s 5,100 jails, and state and federal prisons, but her group found that prison staffers have broken prisoners’ jaws, noses and ribs and left them with lacerations requiring stitches, second-degree burns, deep bruises and damaged internal organs.

In some cases, she said, the amount of force the staff has used has led to the deaths of mentally ill prisoners, such as 35-year-old Christopher Lopez.

Lopez, suffering from “schizoaffective disorder, bipolar type,” was found lying face down on the floor of his cell at 3:30 a.m. March 17, 2013, by workers in a Colorado prison. He was barely able to move, according to the report.

Instead of calling for medical help or taking him to the prison clinic, officers handcuffed him, fastened the cuffs to a belly chain, shackled Lopez’s ankles and chained him to a “restraint chair.”

When prison staff removed Lopez from the chair a couple of hours later and left him on the floor, still in restraints, his breathing was labored, the report said. In a graphic video, Lopez can be seen having a seizure.

“It was clearly audible and visible from where all the guards were, and no one lifts a finger to help him,” David Lane, the attorney for Lopez’s family, said in the video. He died at about 9 a.m. from hyponatremia, a blood condition that is treatable with prompt medical attention.

“Prisoners with mental illness are more likely to have disciplinary problems, to wind up in solitary confinement and to be subjected to use of force by corrections staff,” said Eldon Vail, former Washington state secretary of corrections.

Deborah Golden, director of the D.C. Prisoners’ Project, which represents D.C. inmates in federal prisons, said that the largest number of requests for assistance involve issues revolving around inappropriate mental health care or use of force against mentally ill inmates.

Human Rights Watch recommends that officials reduce the number of inmates with mental disabilities confined to prison by increasing the availability of community health resources and access to programs that divert offenders out of the criminal justice system and into treatment. The group also calls for improved mental health services that address the needs and vulnerabilities of mentally ill prisoners.

“Custody staff are not trained in how to work with prisoners with mental disabilities, how to defuse volatile situations or how to talk prisoners into complying with orders,” Fellner said. “All too often, force is what staff members know and what they use.”