A Minnesota federal grand jury has indicted Derek Chauvin and three other former Minneapolis police officers with civil rights violations for their lethal arrest of George Floyd, which sparked a nationwide racial justice movement, according to documents unsealed Friday.

Another indictment accused Chauvin of violating the civil rights of a teenager during a 2017 on-the-job assault.

Chauvin was recently convicted in state court of murdering Floyd last Memorial Day while arresting him for allegedly using a $20 counterfeit bill at a convenience store. Chauvin pressed his knee into Floyd's neck for more than nine minutes as Floyd, who lay handcuffed face-down on the ground, begged the officer to stop, said he couldn't breathe and eventually lost consciousness.

Two other officers — J. Alexander Kueng and Thomas Lane — also restrained Floyd, while officer Tou Thao watched a crowd of bystanders who warned police they were killing Floyd. One of those bystanders shot a cellphone video of the killing, which was viewed by millions. The image of a Black man gasping for breath under the knee of a white police officer sparked a nationwide racial justice movement last summer.

The new indictment claims that the officers robbed Floyd of his constitutional right "not to be deprived of liberty without due process of law, which includes an arrestee's right to be free from a police officer's deliberate indifference to his serious medical needs."

Federal prosecutors also accused Chauvin of violating Floyd's "right to be free from the use of unreasonable force by a police officer," and accused Thao and Kueng of "willfully fail[ing] to intervene to stop defendant Chauvin's use of unreasonable force."

"Chauvin held his left knee across George Floyd's neck, and his right knee on Floyd's back and arm, as George Floyd lay on the ground, handcuffed and unresisting, and kept his knees on Floyd's neck and body even after Floyd became unresponsive," the indictment said. "This offense resulted in bodily injury to, and the death of George Floyd."

Representatives for the U.S. Department of Justice and the Minnesota U.S. Attorney's Office did not comment on the new charges.

Stanford law professor David Alan Sklansky told Law360 that the case signals the Justice Department acknowledges its role in upholding constitutional rights.

"I think it's a recognition that the federal government has a distinct interest in prosecuting police who violate federal civil rights," he said.

A separate indictment also unsealed Friday charged Chauvin with civil rights violations for allegedly assaulting a 14-year-old in 2017. Chauvin is accused of holding the teen by the throat and striking him multiple times in the head with a flashlight.

The indictment also describes Chauvin of restraining the teenager with a technique similar to the one that killed Floyd, alleging he "held his knee on the neck and the upper back" of the child, who was "lying prone, handcuffed, and unresisting."

That was striking to Alexis Hoag, a Columbia Law School professor and former senior counsel at the NAACP Legal Defense and Educational Fund. During Chauvin's trial in state court last month, a slew of Minneapolis police officers testified that the way Chauvin treated Floyd went against the department's ethos and training. Yet, Hoag noted, Chauvin continued not only to serve on the force, but to train younger officers after the 2017 incident.

"It's a more systemic issue," she said. "Despite the Minneapolis Police Department's characterization of Derek Chauvin as a single bad apple, it's a much larger issue at stake here."

Chauvin was found guilty last month of murdering Floyd after a three-week criminal trial in Hennepin County District Court. Jurors convicted him of second-degree murder, third-degree murder and second-degree manslaughter.

The other three officers have been charged in Hennepin County court with aiding and abetting second-degree murder and aiding and abetting second-degree manslaughter. Their cases are expected to go to trial in August.

The attorneys representing the four defendants in the state court cases did not immediately respond to requests for comment.

In spite of Chauvin's conviction in state court, the federal case will be more difficult to prove, according to Robert Driscoll of McGlinchey Stafford PLLC, who served as chief of staff of the DOJ's Civil Rights Division during the George W. Bush administration.

Driscoll told Law360 that securing a civil rights conviction against all four officers could be an "uphill climb," especially for Lane and Thao, who'd been on the job for less than a week last Memorial Day.

The case could very well go to trial, he said, but "these are hard cases to win."

"Intent is a huge factor in federal civil rights charges," Driscoll said. "There are plenty of things you can do that are bad decisions, that are bad police work, but that are not criminal from a federal civil rights perspective."

The DOJ announced last month that it opened a separate civil investigation into the Minneapolis Police Department. Attorney General Merrick Garland said the agency would "assess whether the Minneapolis Police Department engages in a pattern or practice of using excessive force, including during protests."

Hoag said the indictments, coming after this investigation, were politically significant.

"President Joe Biden, through Attorney General Merrick Garland, is showing that the federal government is willing to step in and at least give the appearance of prioritizing racial justice in the context of excessive use of force from police officers," she said.

The government is represented by Samantha Trepel and Tara Allison of the DOJ's Civil Rights Division; and W. Anders Folk, Samantha Bates, LeeAnn Bell, Evan Gilead, Manda Sertich and Allen Slaughter of the U.S. Attorney's Office for the District of Minnesota.

Attorney information for the defendants was not immediately available.

The cases are U.S. v. Chauvin, case number 0:21-cr-00109, and U.S. v. Chauvin et al., case number 0:21-cr-00108, in U.S. District Court for the District of Minnesota.

--Editing by Adam LoBelia.