U.S. officials have charged an Arizona inmate with seriously injuring Derek Chauvin, the former Minneapolis police officer convicted of killing George Floyd, in a prison stabbing attack last week.

An inmate was killed Wednesday in an attack by two other prisoners at a maximum-security facility in California.

Derek Chauvin has returned to prison after the former Minneapolis police officer was stabbed 22 times by a fellow inmate, his attorney said.

While Chauvin's family members are grateful for his recovery, they remain "very concerned about the facility's capacity to protect Derek from further harm," the attorney said.