Building on their work exposing violence and abuse on Rikers Island all year, the Times obtained a secret study conducted by the Department of Health showing that over an 11-month period, 129 inmates were seriously injured by Correction Department officers. In 80% of the cases, the inmates were beaten after being handcuffed; 77% of the injured inmates have been diagnosed with mental illness.

None of the officers involved in the 129 cases have been prosecuted or have been made to answer to internal charges.

The report shows what advocates have been saying for years: Rikers Island is failing to provide mentally ill inmates with adequate care. Currently, Rikers has roughly the same amount of mentally ill inmates (4,000) as all 24 psychiatric hospitals in the state combined, comprising 40% of the inmate population there. These inmates often throw urine or feces on the officers and lash out towards the guards, who violently tamp down any and every offense, no matter how minor.

The Times story homes in on the case of Jose Bautista, who attempted to hang himself because he feared deportation. After officers cut him down, Bautista stood up, and was beaten so severely that his bowels were ruptured. Instead of taking him directly to the hospital, the guards allegedly gave him "bus therapy."

There is a charade at Rikers, widely known by jail employees and jokingly referred to by some as “bus therapy” — where guards will load an inmate they do not want around into a van and drive him in circles.

This may have been what happened to Mr. Bautista. The jail log had him leaving the clinic at 5:45 p.m. on Jan. 11 and being admitted to Elmhurst Hospital Center at 2:47 a.m. on Jan. 12, according to investigators.

It is a 15-minute drive.

Mr. Bautista said it was past midnight when a second van ride took him to the hospital.

When he reached the emergency room, he asked to call his wife but was told by doctors there was no time: He was in danger of dying.

The Correction Officers' Benevolent Association has vehemently denied that their members frequently resort to excessive force, despite the DOH report showing that 73% of the injuries sustained by the inmates were on their heads and faces.

COBA's president, Norman Seabrook, openly disdains the DOH and the new Correction Commissioner appointed by Mayor de Blasio, Joseph Ponte.

Tensions over how to handle inmates with mental illnesses surfaced recently while Mr. Ponte, Mr. Seabrook and Dr. Mary Travis Bassett, the health commissioner, were touring the Central Punitive Segregation Unit at Rikers. Inmates there are locked in solitary for 23 hours a day. As health officials were explaining the screening process that is supposed to be used before an inmate with a mental illness is placed in segregation, Mr. Seabrook erupted, according to two people who were there.

He asked Dr. Bassett how she would feel if his officers suddenly disappeared from the cellblock, leaving her alone with 100 vicious inmates — and then he answered his own question.

You’d be soiling your pants, he told her. (His words were more graphic.)

“This jail belongs to us,” Mr. Seabrook yelled. “It does not belong to the department of mental health.”