Mr Chauvin, 44, has been charged with second-degree murder, which carries a sentence of up to 40 years in prison, and with manslaughter.

He could potentially also face a third charge of third-degree murder after the Minnesota Court of Appeals ruled on Friday that a lower court had erred in dismissing the count in October, empowering state attorney general Keith Ellison to reinstate it.

Floyd’s death last year followed an altercation at the Cup Foods grocery store in Minneapolis, which the 46-year-old had entered to buy a packet of cigarettes before being accused of attempting to pay with a counterfeit $20 bill by the cashier.

Police were called to resolve the dispute, whereupon Officer Chauvin arrested Floyd and handcuffed him and was then seen shoving him to the pavement and pressing his knee into the accused’s neck, holding it there for seven minutes and 46 seconds, according to prosecutors.

Three other officers held back a crowd of bystanders, with several filming the incident on their phones, resulting in the shocking videos watched by millions online of Officer Chauvin ignoring Floyd’s repeated warnings that he could not breathe until his body finally went limp.

He was declared dead in hospital an hour later.

The killing provoked outrage and resulted in one of the largest protest movements ever seen in the United States, with nightly marches spreading to cities across the country and later to Europe, with participants decrying police brutality and institutional racism.

The emotionally charged nature of the case has meant the judge overseeing Mr Chauvin’s trial at the Hennepin County Government Center in the Midwestern city has allowed three weeks for jury selection alone, with the arguments in the case not scheduled to commence until 29 March.

Potential jurors are being asked to complete a 16-page questionnaire as part of an effort to root out bias, the survey asking them whether they have seen the mobile footage of Floyd’s final moments, whether they took part in the Black Lives Matter protests themselves and what their opinion of the movement is.

Twelve candidates will eventually be chosen, with four more in reserve in the event of objections from either side.

Mr Chauvin’s lawyers have up to 15 peremptory challenges by which they can exclude a juror without having to cite a reason, while the prosecutors from the Minnesota attorney general’s office have nine.

If one side suspects the other is challenging a juror on the basis of their race, ethnicity or sex, they can ask the judge to overrule.

Some criminal justice experts fear the ultimate lineup may not include any black members, despite one fifth of the city’s citizens being African American, which threatens to undermine the validity of any eventual verdict in the eyes of the public.

“What all of us should be wanting is a jury that represents the range of views and opinions and demographic characteristics of the community,” Valerie Hans, a law professor at Cornell University who studies the jury system, said in an interview. “That should include people that maybe were in protests and have a variety of views on the related issues.”

In defending Mr Chauvin, his attorneys are expected to contest the cause of Floyd’s death.

A state medical examiner originally ruled the matter a homicide caused partly by police restraint holds, but his autopsy report also noted that Floyd had recently ingested the opioid fentanyl, with Mr Chauvin’s lawyers contending that an overdose was the primary cause of his death, not the officer’s actions.

Social restrictions in response to the ongoing coronavirus pandemic are expected to further complicate the trial.

It will stream online (an unusual step for a US murder case), only one Chauvin or Floyd family member will be allowed into the courtroom while his fellow ex-officers who were at the scene – J Alexander Kueng, Thomas Lane and Tou Thao, all of whom were fired, along with Mr Chauvin, the day after the Floyd incident – will face trial seperately in August.

This month’s proceedings are inevitably being regarded in many quarters as a referendum on police violence against black Americans.

Fears persist that an acquittal for Mr Chauvin could trigger a fresh wave of anger and unrest akin to that seen last summer.

The Hennepin County Government Center has already been ringed with fencing and concrete barricades while, on Sunday, Minneapolis saw a thousand-strong march staged by Black Lives Matter demonstrators, some uniting to carry a long paper scroll recording the names of more than 470 black Americans they said had been slain by Minneapolis police and others hauling a coffin with George Floyd’s picture on it as part of their pointed call for justice.

Additional reporting by Reuters