Booking photo of Derek Chauvin released by the Minnesota Department of Corrections on April 21.
CNN  — 

Former Minneapolis police officer Derek Chauvin, who was convicted in April on state murder charges for killing George Floyd, pleaded not guilty on Thursday in a federal case related to the use of unreasonable force on a 14-year-old in September 2017.

Chauvin was arraigned via video conference before US District Magistrate Judge Hildy Bowbeer on two counts of federal civil rights violations. He declined to have the charges read against him in court.

The ex-cop wore a tan shirt in what appeared to be a conference room – a yellow pad in front of him – at Minnesota’s maximum-security prison in Oak Park Heights outside of Minneapolis, where he’s serving a 22 1/2-year sentence for Floyd’s murder. He spoke briefly, answering short procedural questions and entering his plea.

A federal grand jury indicted Chauvin and three other former officers in May for allegedly violating Floyd’s constitutional rights.

Chauvin also was charged in the separate indictment involving the Minneapolis 14-year-old in September 2017, according to the Justice Department.

The first count of that indictment said Chauvin “held the teenager by the throat and struck the teenager multiple times in the head with a flashlight,” the DOJ said in a statement at the time.

A second count said the former officer “held his knee on the neck and the upper back of the teenager even after the teenager was lying prone, handcuffed, and unresisting, also resulting in bodily injury.”

Chauvin is accused of willfully depriving the teenager’s “constitutional right to be free from the use of unreasonable force by a police officer,” according to a DOJ statement at the time.

Floyd’s death on May 25, 2020, ignited nationwide protests against police brutality and racial injustice.

Bystander video showed Chauvin kneeling on Floyd’s neck for 9 minutes and 29 seconds while the 46-year-old, handcuffed and lying prone in the street, gasped for air, telling the officers, “I can’t breathe.”

Chauvin and former officers Tou Thao, J. Alexander Kueng and Thomas Lane on Tuesday pleaded not guilty to federal civil rights charges stemming from Floyd’s death.

Chauvin is accused of depriving Floyd’s right to be free from “unreasonable seizure, which includes the right to be free from the use of unreasonable force by a police officer.”

Thao and Kueng also were charged in connection with their failure to intervene in Chauvin’s use of unreasonable force, according to the indictment. Chauvin, Thao, Kueng and Lane also face a charge for failing to give Floyd medical aid.

The indictment said “the defendants saw George Floyd lying on the ground in clear need of medical care, and willfully failed to aid Floyd, thereby acting with deliberate indifference to a substantial risk of harm to Floyd.”

Trial dates have not been set in the federal cases.

Separately, Thao, Kueng and Lane are charged in a state court for aiding and abetting second-degree murder and aiding and abetting second-degree manslaughter in Floyd’s death. They have pleaded not guilty.

Thao, Kueng and Lane were on the scene with Chauvin when Floyd was killed.

The federal charges against the ex-cops are separate from a civil investigation into Minneapolis policing practices announced by Attorney General Merrick Garland in April.