The Justice Department has opened an investigation into the killing of George Floyd

• Attorney General William Barr announced Friday that the Justice Department, including the FBI, was investigating the death of George Floyd, a black man who died after a white police officer knelt on his neck for eight minutes.
• The department is "conducting an independent investigation to determine whether any federal civil-rights laws were violated" related to Floyd's arrest and subsequent death, Barr said in a statement.
• Earlier Friday, Hennepin County prosecutors charged former Minneapolis police officer Derek Chauvin, who was filmed kneeling on Floyd, with third-degree murder in the case.
• The attorney general called video images of the incident "harrowing to watch and deeply disturbing."
• A former federal prosecutor told Business Insider that it was unusual for the Justice Department to get involved so early in the process and it typically doesn't intervene unless state prosecutors have already tried and failed to charge or convict a police officer.
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Attorney General William Barr on Friday announced a federal investigation into the killing of George Floyd, a black man who died after a white police officer knelt on his neck for eight minutes.

Barr said in a statement Friday that a state prosecutor "has been in the process of determining whether any criminal charges are appropriate under state law."

He added that the Justice Department, including the FBI, was also "conducting an independent investigation to determine whether any federal civil-rights laws were violated" related to Floyd's death.

Earlier Friday, Hennepin County prosecutors charged former Minneapolis police officer Derek Chauvin, who was filmed kneeling on Floyd, with third-degree murder in the case.

Barr said in his statement that state and federal officers "are working diligently and collaboratively to ensure that any available evidence relevant to these decisions is obtained as quickly as possible."

He called video images of the incident "harrowing to watch and deeply disturbing."

"Under our system, charging decisions must be, and will be, based on the law and facts," the statement said. "This process is proceeding quickly. As is the typical practice, the state's charging decisions will be made first. I am confident justice will be served."

It's unusual for the Justice Department to get involved so early in the process, Mark Osler, a former federal prosecutor and law professor at the University of St. Thomas in Minnesota, told Business Insider.

Osler said the department typically doesn't intervene unless state prosecutors have already tried and failed to charge or convict a police officer.

"Straight-up murder isn't a federal offense," he said, noting there were limited exceptions, such as if the murder took place on a military base. "There's a federal law against the violation of civil rights, but usually that doesn't happen until after murder charges fail."

Osler continued: "Usually what you're going to see is the state make the case for murder, and then if they fail, the feds would step in."

He likened the situation to the ex-LAPD officers Stacey Koon and Laurence Powell, who were videotaped beating Rodney King in 1991. The men were first acquitted on state charges, but federal authorities pursued the case, and both men were later convicted of federal charges of violating King's civil rights.

Floyd's death sparked widespread outrage and prompted thousands of people to protest police brutality against black men. The demonstrations started in Minneapolis on Thursday and have continued spreading across the US since.

President Donald Trump weighed in on the protests, calling the demonstrators "thugs" and threatening to send in the National Guard.

"These THUGS are dishonoring the memory of George Floyd, and I won't let that happen. Just spoke to Governor Tim Walz and told him that the Military is with him all the way. Any difficulty and we will assume control but, when the looting starts, the shooting starts. Thank you!" Trump wrote in a tweet.

Shortly after, Twitter flagged the tweet with a "public interest notice," which warned that it "violated the Twitter Rules about glorifying violence."

However, the social-media company did not take down the tweet, saying was "in the public's interest" for Trump's tweet to remain accessible, though users can no longer reply, like, or retweet it.