On Tuesday, three California jail deputies were charged with what their boss called the “vile and cowardly” murder of Michael Tyree, a homeless man who was found beaten death in his cell last month while awaiting transfer to a mental health facility.

“They may have thought that their violence, enacted late at night in the obscurity of a jail cell and against a helpless and mentally ill inmate, was invisible,” said Santa Clara County District Attorney Jeff Rosen in a statement. “Today we see it for all of its brutality. Mr. Tyree was not invisible. His death was not invisible. We will see that there is justice.”

Police say the fatal beating occurred at around 11 p.m. on August 26, when Deputies Matthew Farris, Jereh Lubrin and Rafael Rodriguez began searching cells in Santa Clara County Main Jail’s special needs wing. From the L.A. Times:

When the jail deputies got to Tyree’s cell, he was heard saying, “Do I have to get up?” at which point, Farris ordered Tyree to get up, [Sgt. Marc] Carrasco said.

Tyree was heard screaming, “I’m sorry. I’m sorry. Stop.”

Minutes of screaming, thumping, wall-banging and “what sounded like blows to a person’s body” were heard throughout the cell unit, Carrasco said.

Tyree had injuries above his eye, near his chin, on his cheek and on his arms, legs, back and hips.

During a welfare check about an hour later, Tyree was reportedly found naked, unresponsive and covered in feces and vomit. At 12:35 a.m., he was pronounced dead.

In addition to murder, Farris, Lubrin and Rodriguez each face one count of assault under the color of authority for allegedly beating another inmate earlier the same evening. If convicted, the deputies face life in prison.

“The disappointment and disgust I feel cannot be overstated,” said Santa Clara County Sheriff Laurie Smith at a press conference last week. “His life had value.”

[Image via KPIX//h/t Raw Story]