WASHINGTON, Sep 14. Former U.S. police officer Derek Chauvin, who was sentenced to twenty-two years in prison for the murder of African American George Floyd, and three of his former colleagues pleaded not guilty in the Federal Court. Ex-police officers Derek Chauvin, Thomas Lane, Jay Keng and Tou Tao, who participated in the arrest of Floyd in May 2020, are accused of abuse of power and violation of his legal rights. The specific articles of the charge vary: Chauvin is accused of wrongful seizure and unjustified use of excessive force. The other two are accused of not interfering with a colleague, and all four of them are accused of not providing Floyd with proper medical attention. All four former police officers spoke at the meeting via video link. In accordance with the rules, the judge leading the trial asked the defendants in the case whether they admitted guilt, to which he received negative answers. A number of various technical issues were also considered at the meeting, including a request to conduct separate proceedings against clients. Lawyers for three ex-police officers fear that the joint trial with Chauvin could negatively affect the decision in the case of their clients. The murder of African American Floyd by white policeman Chauvin on May 25, 2020 provoked mass protests and riots throughout the United States, as well as public discussion about the need to reform the police. In June 2021, a Minneapolis court sentenced Chauvin to 22.5 years in prison. The state trial for the three other police officers will begin in March. Biden commented on the sentence of the ex-policeman for the murder of Floyd