MINNEAPOLIS (AP) — Four former Minneapolis police officers charged with violating George Floyd’s civil rights pleaded not guilty Tuesday to the federal charges against them.

A federal grand jury indicted Derek Chauvin, Thomas Lane, J. Kueng and Tou Thao in May for allegedly depriving Floyd of his rights while acting under government authority on May 25, 2020, as Floyd, 46, was held face-down, handcuffed and not resisting in a restraint that was captured on bystander video. His death led to worldwide protests and calls for change in policing.

All four of the men appeared at the hearing remotely via videoconference. Chauvin appeared from a room in the state’s maximum security prison, where he is serving a 22 1/2-year sentence for murder in Floyd’s death. The other three men appeared remotely alongside their attorneys.

Prosecutors and attorneys for the former officers are also arguing about 40 pretrial motions on Tuesday.

Among them, Kueng and Thao have asked that their federal trials be separated from Chauvin’s, saying they would be unfairly prejudiced if they went to trial alongside him. Lane asked to join that request, which is being opposed by prosecutors. It wasn’t immediately clear if that issue will come up at Tuesday’s hearing, because both sides have agreed the request was premature and have asked to set it aside until more information develops, according to court documents. But U.S. Magistrate Judge Tony Leung indicated at the start of the hearing that it would be addressed.

The federal indictment alleges Chauvin violated Floyd’s right to be free from unreasonable seizure and unreasonable force by a police officer. Thao and Kueng are charged with violating Floyd’s right to be free from unreasonable seizure by not intervening to stop Chauvin as he knelt on Floyd’s neck. All four officers are also charged with depriving Floyd of his rights when they failed to provide him with medical care.

During Floyd’s arrest, he repeatedly said he couldn’t breathe as Chauvin pinned him to the ground. Kueng and Lane helped restrain Floyd; Kueng knelt on Floyd’s back, and Lane held Floyd’s legs, according to evidence in state court. Thao held back bystanders and kept them from intervening during the 9 1/2-minute restraint.

The four officers were also charged in state court, where Chauvin’s trial was eventually separated from the others due to space restrictions during the COVID-19 pandemic. Chauvin was convicted in April of murder and manslaughter and was sentenced to 22 1/2 years. The other three former officers face state trial next March on aiding and abetting counts.

Chauvin is also charged in a separate federal indictment alleging he violated the civil rights of a 14-year-old boy in 2017.

Meanwhile, the federal government is investigating policing practices in Minneapolis. The investigation known as a “pattern or practice” — examining whether there is a pattern or practice of unconstitutional or unlawful policing — includes a sweeping review of the entire police department. It may result in major changes to policing in the Minnesota city.