Minnesota’s attorney general added an upgraded charge of second-degree murder against one former police officer and charged three others in the death of George Floyd, in a fast-moving investigation of the killing that has sparked nationwide protests.
George Floyd, 46, died after Derek Chauvin, a white policeman, knelt on his neck for nearly nine minutes on May 25, reigniting the explosive issue of police brutality against African Americans five months before a presidential election.
The charge against Derek Chauvin has been elevated to second-degree murder, court documents show.
The other three officers, previously uncharged, face counts of aiding and abetting murder.
Floyd's death has sparked huge protests across the US against racism and the police killings of black Americans.
The vast majority of demonstrations over the past eight days have been peaceful, but some have turned violent and curfews have been imposed in a number of cities.
Announcing the new charges, Minnesota's Attorney General Keith Ellison said that they were in the interests of justice.
Derek Chauvin had initially faced charges of third-degree murder and second-degree manslaughter. These will stay on his charge sheet.
The other three sacked officers are Thomas Lane, J Alexander Kueng and Tou Thao. They all face charges of aiding and abetting second-degree murder, and aiding and abetting second-degree manslaughter.
Minnesota Senator Amy Klobuchar said on Twitter that the latest charges were "another important step for justice".