Former Minneapolis police officer Derek Chauvin pleaded guilty on Wednesday in federal court to violating George Floyd's civil rights in the black man's murder, reversing his not-guilty plea from September.
He faces a maximum penalty of life imprisonment, although an agreement to plead guilty could result in prosecutors asking for a lighter sentence.
Chauvin has already been sentenced to 22.5 years in prison in state court for the 2020 murder of Floyd, on whose neck the former policeman knelt for more than nine minutes while a bystander captured it on her mobile phone.
His April conviction in state court on charges of unintentional second-degree murder, third-degree murder and manslaughter was seen by many as a rebuke of the disproportionate use of police force against black Americans.
The video that showed Chauvin kneeling on the neck of the handcuffed Floyd during the arrest caused global outrage — and triggered one of the biggest protest movements in the US in decades.
Three other officers as well as Chauvin — Thomas Lane, J Alexander Kueng and Tou Thao — were arresting Floyd on suspicion of using a fake $20 bill. The three officers are facing charges in a state trial due to begin in March over their alleged aiding and abetting of Floyd's killing.
In addition to the state charges, all four officers were federally indicted in May on charges of depriving Floyd of his civil rights by failing to provide him with medical attention.
Chauvin was also federally charged with violating Floyd's right to be free from unreasonable seizure and unreasonable force by a police officer.
Mr Thao and Mr Kueng have been federally charged with violating Floyd's right to be free from unreasonable seizure by not intervening to stop Chauvin from kneeling on Floyd's neck.