Posters are seen during protests against racial injustice to mark Juneteenth, commemorating the end of slavery in the United States, near the White House in Washington, D.C., the United States, June 19, 2020. This year's Juneteenth comes amid nationwide demonstrations against police brutality and racism triggered by the death of George Floyd in police custody. More than 20 rallies, marches and events were scheduled for Friday in Washington, D.C., with hundreds more in over 40 states, according to the Movement for Black Lives, a coalition of U.S. groups representing the interests of black communities.Photo:Xinhua

George Floyd must receive justice, his family said ahead of opening arguments on Monday in the trial of the white police officer accused of killing the Black man, whose agonizing death ignited protests against racism and police brutality across the US and around the world.

"I have a big hole right now in my heart. It can't be patched up ... I need justice for George. We need a conviction," Floyd's brother Philonise told reporters in Minneapolis on Sunday. 

Derek Chauvin, a veteran of the Minneapolis Police Department, faces murder and manslaughter charges for his role in the May 25, 2020 death of the 46-year-old Floyd.

Chauvin, 44, who was fired from the police force along with three other officers, could be sentenced to up to 40 years in prison if convicted of the most serious charge - second-degree murder.

The Minneapolis-based StarTribune newspaper called the trial "a defining moment in America's racial history."

Floyd's cause of death is expected to be the central issue in the case, and a key piece of evidence is likely to be the bystander-filmed video of his death that went viral and triggered a summer of anti-racism protests.

Chauvin was seen in the video kneeling on Floyd's neck for nearly nine minutes while arresting him for allegedly passing a counterfeit $20 bill.

Chauvin's attorney, Eric Nelson, was expected to argue that the officer was following police procedure and claim that Floyd's death was due to an overdose of the drug fentanyl and underlying health conditions.