A jury has found former Minneapolis police officer Derek Chauvin guilty of murder and manslaughter after kneeling on the neck of a dying George Floyd during an arrest last May.
The verdict was read in court on Tuesday morning, with Chauvin found guilty of second-degree unintentional murder, third-degree "depraved mind" murder and second-degree manslaughter.
The 12 sequestered jurors have considered three weeks of testimony from 45 witnesses including bystanders, police officials and medical experts along with hours of video evidence in the most high-profile US case involving accusations of police misconduct in decades.
Jurors had reached a unanimous verdict on each charge to convict or acquit. A single hold-out would have resulted result in a mistrial.
All three charges required that jurors found Chauvin's acts were a "substantial causal factor" in Floyd's death but none required they find he intended to kill Floyd.
In an arrest captured on video, Chauvin pushed his knee into the neck of Floyd, a 46-year-old handcuffed black man, for more than nine minutes outside the grocery store where Floyd had been accused of buying cigarettes with a fake $US20 banknote.
Floyd's relatives, many of them travelling from Texas, have taken turns sitting in a single chair reserved for them in the courtroom.
US President Joe Biden spoke with Floyd's family on Monday "to check in with them and also share that the family was in his prayers", White House Press Secretary Jen Psaki said.
With the jurors sequestered, Biden told reporters at the White House he was praying for the "right verdict" in the most high-profile US case involving accusations of police misconduct in decades.
Angela Harrelson, an aunt of Floyd, wrote in a text message the family was "waiting nervously" for the verdict.
The case hinged on whether the jury believed the prosecution argument that Chauvin used excessive, and therefore illegal, force that killed Floyd.
The defence countered that Chauvin behaved as any "reasonable police officer" would, and sought to raise doubts about the cause of Floyd's death, saying heart disease or even the exhaust fumes from the nearby police car may have been factors.
The courthouse was surrounded by high barricades and guarded by National Guard troops.
Many downtown businesses boarded up their windows for fear of a repeat of the violent street clashes that unfolded last year between police in riot gear and protesters, some of whom set fire to a police precinct house and damaged nearby property.
-- with AAP