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Minnesota Attorney General Keith Ellison announced Wednesday that he has formally filed charges against the three remaining officers involved in last week's killing of George Floyd with "aiding and abetting" second-degree murder, a felony, and also filed a motion to elevate the charges against officer Derek Chauvin, already under arrest, from third-degree to second-degree murder.

"I strongly believe that these developments are in the interest of justice for Mr. Floyd, his family, our community, and our state," Ellison said.

Ellison said that arrest warrants had been issued for the newly-charged officers—Tou Thao, Thomas Lane and J. Alexander Kueng—and also made it clear he would be the lead prosecutor as the cases make their way through the courts.

Ellison held a press conference just before 4:00pm local time. Watch:

"Overdue but necessary justice," tweeted Rep. Ilhan Omar (D-Minn.)

As NBC News reports:

Former officers Tou Thao, Thomas Lane and J. Alexander Kueng are facing charges of aiding and abetting murder, according to criminal complaints filed by the state of Minnesota on Wednesday. The murder charge against another former officer, Derek Chauvin, were also elevated to second-degree murder.

The Floyd family, in a statement through their attorney, Ben Crump, called the news of the charges a "bittersweet moment."

It's unclear if the arrests will calm an angry nation. Protesters around the country turned out Tuesday evening for the eighth consecutive night of demonstrations over Floyd's murder.

As the New York Times reported:

While demonstrators in many cities defied curfews, they did so peacefully.

They sang “We Shall Overcome” at the Barclay's Center in Brooklyn and a large crowd tried to cross over the Manhattan bridge in defiance of a curfew. Outside Wrigley Field in Chicago, crowds chanted "Hands up" as they raised their arms to the sky. In Los Angeles, even as hundreds were arrested throughout the city, a crowd gathered outside the home of Mayor Eric Garcetti, who earlier in the day had joined the demonstrations and taken a knee as he listened to pleas. On a bridge in Portland, Ore., hundreds lay face down, hands behind their backs, for a "die in" intended to emulate the death of George Floyd.

Mr. Floyd, a 46-year-old black security guard, died after his neck was pinned under a white police officer’s knee for nearly nine minutes in Minneapolis last week. The officer has been charged with third-degree murder and second-degree manslaughter. The killing, captured on video, was the spark for the outpouring of anger and anguish expressed in demonstrations in more than 140 cities for over a week.

At least 9,300 U.S. civilians have been arrested due to their participation in an ongoing nationwide uprising against police violence and brutality sparked by Floyd's murder.

That tally comes from the Associated Press, which has been tracking the arrests around the country.

Activist group CodePink tweeted that the struggle was ongoing. 

"This is just the beginning," the group said. "We must continue demanding #JusticeForGeorgeFloyd! #BlackLivesMatter."