A fellow inmate stabbed former police officer Derek Chauvin more than 20 times, US prosecutors said as they announced charges of attempted murder.
Chauvin, whose killing of George Floyd in Minnesota sparked massive racial justice protests in 2020, was attacked in the law library of an Arizona prison last month.
Chauvin was sentenced to over two decades in prison after being convicted of the murder of the 46-year-old black man, on whose neck he knelt for nine minutes.
Suspect John Turscak, aged 52, told investigators the date of his attack, Black Friday, the day after Thanksgiving, was intended to invoke the Black Lives Matter movement, according to the criminal complaint.
"Turscak told the corrections officers that he would have killed (Chauvin) had they not responded so quickly," the complaint says.
The US District Attorney's Office in Tucson said it had charged Turscak with attempted murder, assault with intent to commit murder, assault with a dangerous weapon and assault resulting in serious bodily injury.
"Turscak stabbed another inmate, D.C., who had previously been convicted of federal crimes in another district, approximately 22 times with an improvised knife," a statement said.
Attempted murder carries a sentence of up to 20 years in prison.
There was no further information on Chauvin's condition.
Chauvin was found guilty of second-degree murder, third-degree murder and second-degree manslaughter in 2021, and sentenced to 22-and-a-half years in prison.
The death of Mr Floyd was caught on video, providing a drastically different version of events than the initial police news release, which simply stated "officers were able to get the suspect into handcuffs and noted he appeared to be suffering medical distress".
A Justice Department probe into the Minneapolis police, the findings of which were published in June 2023, said that officers in the department routinely resorted to violent and racist practices, "including unjustified deadly force".
The city of Minneapolis, in the midwestern state of Minnesota, also settled a wrongful death lawsuit filed by the Floyd family, agreeing to pay his relatives $27 million.
Chauvin unsuccessfully appealed his second-degree murder conviction.
