In a devastating investigation published on Monday, the New York Times details horrific abuses of mentally ill inmates taking place at the hands of guards behind the walls of New York City’s Rikers Island jail. In an 11-month span last year, 129 inmates at Rikers Island were seriously injured in "altercations" with guards, and more than three-quarters of them had received a mental illness diagnosis. Inmates have been getting beat up so badly that they require stitches, emergency surgery or care for broken bones.

Here are just two of multiple incidents New York Times reporters Michael Winerip and Michael Schwirtz uncovered in their investigation:

In August, Carlos Gonzalez, who suffered from depression and schizophrenia, was holding hands with his fiancée in a visiting area when a guard told him to let go. The guard threw him against a wall and told him to apologize for continuing to hold on, according to a Legal Aid Society complaint. In Mr. Gonzalez’s version of the events, he said he was sorry, but the guard told him to say it louder. When Mr. Gonzalez, who was arrested for violating an order of protection, refused, he said two guards punched him in the face. Mr. Gonzalez’s eardrum was ruptured, and he was so bloodied the guards made him change into a clean jumpsuit before he was taken to a clinic and later to Elmhurst Hospital Center.

In Brian Mack’s case, guards were allegedly settling a score. Mr. Mack, 57, who has been convicted of grand larceny, told investigators and health officials that he was assaulted in May 2013 by a captain and another officer after the captain challenged him over complaints he made about guards stealing inmates’ food. The captain struck him in the eye with his radio and the officer punched him in his jaw, Mr. Mack told investigators from the correction board.

Medical workers later reported that he had sustained "serious head trauma," including a broken jaw and eye socket. Correction Department officials claimed Mr. Mack’s injuries came from a fight with other inmates, but board investigators could find no record of such a fight in the department’s log books.

It’s a story of aggression and brutality carried out with impunity and against particularly vulnerable inmates. It’s also a snapshot of New York City’s jail as it, like so many around the country, absorbs those with mental illness who might have been housed in other institutions. "Rikers now has about as many people with mental illnesses — roughly 4,000 of the 11,000 inmates — as all 24 psychiatric hospitals in New York State combined," Winerip and Schwirtz write. And the proportions are on the rise. Read the article in full at the New York Times.