At 9.25pm on Monday, May 25, George Floyd died in the custody of the Minneapolis police.

That night, a white police officer had handcuffed the black man for allegedly trying to use a fake $20 bill, before holding him down with a knee on his neck for almost nine minutes, as Floyd pleaded that he could not breathe.

Floyd was pronounced dead in hospital a short time later.

The killing was filmed by bystander Darnella Frazier and has since been seen by hundreds of millions of people. The 46-year-old man’s death has triggered protests across America in all 50 states, as the nation responds to the injustice black citizens continue to experience at the hands of authorities.

All four policemen were quickly fired from the Minneapolis Police Department. And on Wednesday, US time, it was confirmed that all police officers involved in the death of George Floyd have been charged over his murder.

Here’s what we know about their charges.

Derek Chauvin.

Derek Chauvin, who had been with the Minneapolis police department for 19 years, was the man responsible for holding his knee to Floyd's neck, despite the man's desperate pleas that he "can't breathe".

Initially, Chauvin was charged with third-degree murder, which in Minnesota means the suspect acted without regard for human life, but did not intend to kill. He was also charged with second-degree manslaughter.

On Wednesday, his charge was upgraded to second-degree murder. This means the murder was not premeditated, but the defendant did intend to kill. If found guilty, this charge carries a maximum penalty of 40 years in prison.

The former police officer's wife, Kellie Chauvin, filed for divorce from her husband on May 28 - three days after he killed Floyd, and one day before he was charged with third-degree murder.

Tou Thao, J. Alexander Kueng and Thomas Lane.

As Chauvin firmly pressed into the neck of Floyd, two other officers applied pressure with their knees to Floyd's back.

An independent autopsy, done by two doctors hired by Floyd’s family, found that he died by "homicide caused by asphyxia due to neck and back compression that led to a lack of blood flow to the brain". Therefore, the autopsy stated that the pressure applied by the two other officers contributed to the death of Floyd.

A fourth officer watched on.

The three officers, Thomas Lane, 37, J. Alexander Kueng, 26, and Tou Thao, 34, have been charged with aiding and abetting murder, according to criminal complaints filed by the state of Minnesota.

Aiding and abetting second-degree murder is punishable by up to 40 years behind bars, according to Minnesota state law.

Minnesota has also opened a civil rights investigation into whether the Minneapolis Police Department has a pattern of discrimination against minorities.

Minnesota Attorney General Keith Ellison, who filed the new charges, said on Wednesday: "Trying this case will be hard. History does show there are clear challenges here. But we will seek justice and we will find it.

"What I do not believe is one successful prosecution can rectify the hurt and loss that so many people feel. The solution to that pain will be slow and difficult work of construction justice and fairness in our society.

"That work, is the work of all of us."

If you have the means to do so, you can actively help the Black Lives Matter cause in Australia and the United States by donating to organisations working towards racial justice, such as the National Aboriginal and Torres Strait Islander Women’s Alliance and the Justice for David Dungay Fund to support the family of David Dungay Junior, an Aboriginal man who died in a Sydney jail. You can also donate to the Black Lives Matter Global Network here. If you can, consider regularly donating to Indigenous-run organisations and First Nations causes.

Other active ways to help include signing petitions, attending peaceful protests, listening to BIPOC, raising their voices, educating yourself on racism and privilege and ensuring we are all taking part in the conversation to dismantle systemic racism.

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