UTICA, N.Y. (AP) — A prosecutor told a jury Tuesday that three former upstate New York prison guards on trial in the fatal beating of a Black handcuffed inmate took part in an act of “sheer, unimaginable brutality.”

Mathew Galliher, Nicholas Kieffer and David Kingsley are charged with murder and first-degree manslaughter in the death of Robert Brooks, whose beating by guards at the Marcy Correctional Facility on Dec. 9 was captured in part on body-camera footage. The trio were among 10 corrections officers indicted in February on murder charges or for lesser crimes.

Onondaga County District Attorney William Fitzpatrick told jurors in his opening statement that they would view sickening videos of Brooks' treatment by a group of guards, and that each of the defendants was involved.

“They no longer were corrections officers. They were a gang,” Fitzpatrick said in his opening statement. “They took turns — collectively and individually — of punching him, kneeing him, pepper spraying him, choking him, pinning him down, cuffing his legs.”

Brooks, 43, had been serving a 12-year sentence for first-degree assault since 2017 and was transferred to Marcy from a nearby lockup that night. The videos, which triggered widespread outrage, show officers striking him in the chest with a shoe, lifting him by the neck and dropping him.

Defense attorneys told jurors that prosecutors will not be able to prove their clients acted with malice or depraved indifference to human life, as the charges allege. The attorneys asked jurors to take careful note of their clients' specific actions that night.

“The prosecution is attempting to tie Nicholas Kieffer to the actions of others, suggesting to you that he is somehow responsible via association,” said his attorney, David Longeretta.

Galliher's attorney, Kevin Luibrand, said his client has been charged with murder, in large part, for shackling Brooks' legs to keep him from kicking.

“Mathew Galliher didn't harm Robert Brooks. He didn't hit him, he didn't strike him, he didn't encourage others to strike him, he didn't deny him medical care,” Luibrand said. “He didn't do anything that contributed to the death of Robert Brooks.”

Fitzpatrick, the special prosecutor, says Brooks died of a massive beating that broke a bone in his neck, ripped his thyroid cartilage and bruised several internal organs. He also died as a result of repeated restrictions to his airways, which caused brain damage, and choking on his own blood.

Fitzpatrick said Brooks was beaten three separate times as soon as he arrived at the prison, the last being the fatal beating in the infirmary caught on the silent body-camera footage.

A fourth corrections officer is scheduled to go on trial for second-degree manslaughter in January.

Six guards indicted in February have since pleaded guilty. Three more employees have agreed to plead guilty to reduced charges and are cooperating with the special prosecutor.

Fitzpatrick also is prosecuting guards in the fatal beating of Messiah Nantwi on March 1 at another Marcy lockup, the Mid-State Correctional Facility. Ten guards were indicted in April, including two who are charged with murder, in Nantwi's death.

Both prisons are about 180 miles (290 kilometers) northwest of New York City.

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