Sacked US police officer Derek Chauvin will be sentenced on June 16 for the murder of African American George Floyd in a case that sparked nationwide anti-racism protests.

The Hennepin County District Court in the Midwestern city of Minneapolis, where handcuffed Floyd died last May, said in its online schedule that the white ex-cop will be sentenced at 1:30 pm (1830 GMT).

The 45-year-old ex-officer -- who knelt on Floyd's neck for more than nine minutes -- faces up to 40 years in prison after being found guilty of all charges Tuesday over the death of the unarmed man.

The crime was recorded by a bystander whose video shocked the world, triggering mass protests across the United States and beyond, while also prompting a national reckoning on racial injustice and police brutality.

Floyd, 46, was killed as he lay face down and handcuffed, saying repeatedly "I can't breathe." The case prompted some police reforms, but advocates including President Joe Biden say more is needed.

While the Chauvin trial progressed in Minneapolis, the city was rocked by the fatal police shooting of yet another African American, 20-year-old Daunte Wright.

On Wednesday US Attorney General Merrick Garland announced a civil investigation to determine whether the Minneapolis Police Department systematically uses excessive force and "engages in a pattern or practice of unconstitutional or unlawful policing," including during legal protests.

A white ex-police officer is set to be sentenced in June for African-American George Floyd's murder
A white ex-police officer is set to be sentenced in June for African-American George Floyd's murder AFP / Kerem Yucel

The jury deliberated less than 11 hours before finding Chauvin guilty of all three charges against him: second-degree murder, third-degree murder and manslaughter.

A crowd gathered outside the heavily guarded downtown Minneapolis courtroom erupted in cheers, and some wept tears of relief, when the verdicts were announced after a three-week trial that had an entire nation on edge.

Chauvin, who had been free on bail, was put in handcuffs after Hennepin County Judge Peter Cahill read out the unanimous verdicts reached by the racially diverse, seven-woman, five-man jury.

Ahead of the verdict, cities across the United States had been braced for potential unrest and National Guard troops were deployed in Minneapolis.

Floyd was initially arrested on suspicion of a non-violent crime -- trying to pass off a counterfeit $20 bill. His brother Rodney told AFP that Black people had been victims of deadly injustice at the hands of US authorities for hundreds of years.

"We needed a victory in this case, it's very important, and we got it and hey, we might actually breathe a little bit better now," he said.

Three other former police officers involved in Floyd's arrest are to go on trial later this year.