The former Minneapolis police officer convicted in the death of George Floyd was stabbed 22 times by an ex-mafia member in prison.
Derek Chauvin, 47, was attacked by another inmate in Tucson, Arizona, on Friday, November 24.
Former gang leader John Turscak has been charged with attempted murder one week after the attack.
Turscak, who is serving a 30-year sentence for crimes committed while a member of the Mexican Mafia, told investigators he thought about attacking Chauvin for a month because he is a high-profile inmate but denied wanting to kill him, prosecutors said.
Turscak is accused of attacking Chauvin with an improvised knife in the prison law library around 12:30pm on Black Friday, the day after Thanksgiving.
Correctional officers used pepper spray to subdue Turscak, prosecutors said. The US Bureau of Prisons said that "life-saving measures" were performed on the victim
Chauvin was taken to a hospital for treatment. He is believed to be in stable condition.
The attack happened days after the Supreme Court rejected Chauvin's claim that he did not have a fair trial for killing Mr Floyd, 46, who died after Chauvin knelt on his neck for more than nine minutes in Minneapolis in May 2020.
Mr Floyd was suspected of using a counterfeit $20 note at a store. He was handcuffed and a bystander filmed Chauvin kneeling on him as he lay face-down in the street, pleading that he couldn't breathe.
The killing prompted demonstrations around the world against racism and police use of force.
Chauvin was found guilty in 2021 of unintentional second degree murder and jailed for 22 years.