A fired Minneapolis police officer charged alongside two former colleagues with violating George Floyd’s civil rights during the fatal arrest took the witness stand in his own defense on Tuesday.

Tou Thao, 35, is the first defendant charged in the high-profile federal case to speak publicly about his actions during the 2020 episode that prompted nationwide protests and resulted in the murder conviction of his then-senior officer Derek Chauvin in state court last year.

Thao’s co-defendants, J. Alexander Kueng, 28, and Thomas Lane, 38, have also informed U.S. District Court Judge Paul Magnuson that they will testify in the trial taking place in St. Paul, Minnesota.

Thao was among the first witnesses called by the defense a day after prosecutors rested their case.

He testified that as part of his training in the Minneapolis Police Department he was taught to use his knees to keep a suspect pinned to the ground, according to ABC affiliate station KSTP in St. Paul.

Thao’s attorney Robert Paule, displayed for the jury a photo of Thao taken during training in 2009 at the police academy. It showed him and another cadet pinning a handcuffed actor posing as a suspect to the ground in a prone position. Thao explained that he and the other cadet were using their knees to restrain the suspect.

Thao testified that using a knee as leverage prevents a suspect from rolling around or getting up.

“Just to be clear, is this something that was typically taught at the academy when you were there?” Paule asked as he showed the jury several photos of police cadets in training sessions with their knees on the backs and necks of actors pretending to be suspects.

Thao replied, “Yes.”

Several training supervisors from the Minneapolis Police Department testified for the prosecution that all three defendants appeared to ignore their training as the handcuffed Floyd was being held to the ground and became unconscious. Kueng was captured on police body-camera footage played for the jury saying he couldn’t detect Floyd’s pulse.

Prosecutors alleged that none of the defendants did anything to stop Chauvin’s excessive use of force or provide medical assistance to Floyd when he needed it most.

Officer Nicole Mackenzie, the department’s medical support coordinator, testified she personally instructed Lane and Kueng, both rookie police officers at the time of the episode with Floyd, in a police academy “emergency medical responder” class that covered first aid and ethics in care. She also said records show that Thao took a refresher course covering the same topics.

All three men are charged with using the “color of the law,” or their positions as police officers, to deprive Floyd of his civil rights by allegedly showing deliberate indifference to his medical needs as Chauvin kneeled on the back of the handcuffed man’s neck for more than nine minutes, ultimately killing him.

Kueng and Thao both face an additional charge alleging they knew Chauvin was kneeling on Floyd’s neck but did nothing to stop him. Lane, who appeared to express concern for Floyd’s well-being during the encounter, does not face the additional charge.

They have all pleaded not guilty to the charges.

Chauvin was convicted in Minnesota state court in April of second-degree unintentional murder, third-degree murder and second-degree manslaughter. He was sentenced to 22 1/2 years in prison.

Chauvin, 45, also pleaded guilty to federal civil rights charges stemming from Floyd’s death and the abuse of a 14-year-old boy he bashed in the head with a flashlight in 2017. He admitted in the signed plea agreement with federal prosecutors that he knelt on the back of Floyd’s neck even as Floyd complained he could not breathe, fell unconscious and lost a pulse.

This is a developing story. Please check back for updates.