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, saying he “had a different role” than restraining the 46-year-old handcuffed Black man.

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 his dream of becoming a police officer was forged by a childhood experience in which Minneapolis police were called to his home to quell a domestic violence incident involving his abusive father, whom he said beat him and his siblings with an extension cord and threatened them with a gun.

Thao said he was trained to use knees to restrain suspects

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.

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.”

Paule then asked, “Were you ever told it’s improper?”

Thao answered, “No.”

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.

“Super-human strength”

Thao testified that he and Chauvin were partnered up on the day of the Floyd incident. He said they were eating lunch at their precinct when the call came in about Floyd’s arrest outside a Cup Foods store.

He said that as he and Chauvin were responding to back up Lane and Kueng, a dispatcher called them off. But Thao said he and Chauvin continued to drive to Cup Foods.

“From my experience, Cup Foods is hostile to police. It’s a well known Bloods gang hangout,” Thao testified, adding that he figured Lane and Kueng would not have been aware of that because they were rookies.

He said that he and Chauvin were initially just going to act as security in case things got out of hand, but when they arrived they found Lane and Kueng struggling to get a combative Floyd into the back of a squad car.

Thao testified that in his eight years as police officer, he had “never seen this much of a struggle.” He said it appeared that Floyd was on some kind of drugs and that he had “super-human strength that more than three officers could handle.”

He testified that Floyd complained that he couldn’t breathe while the officers were trying to get him into the squad car. He noted that such a complaint “became a regular occurrence” after Eric Garner, a 43-year-old Black man, died in 2014 after a New York City police officer placed him in a banned chokehold and he repeatedly complained, “I can’t breathe.”

“I had a different role”

Thao said that he initially suggested using a hobble device to restrain Floyd, but decided against it because he suspected Floyd was experiencing “excited delirium,” a syndrome in which a subject displays wild agitation and violent behavior that can sometimes lead to death. He said the use of a hobble would have required a sergeant’s approval and could have delayed the arrival of emergency medical services.

He told the jury that as Lane, Kueng and Chauvin restrained Floyd on the ground, he radioed dispatch to step up the EMS response and made himself “a human traffic cone” by standing in the street to keep cars from hitting Floyd and the other officers.

Paule asked Thao what his response was to seeing Chauvin, a training officer, with his knee on the back of Floyd’s neck.

“It was not uncommon. We had been trained on it,” Thao said.

He said he was more focused on keeping at bay a growing crowd that had gathered.

Paule then asked why he didn’t get physically involved in dealing with Floyd. Thao responded, “I had a different role. I assumed they were caring for him.”

“I had no idea”

Thao testified that he didn’t realize the seriousness of Floyd’s condition until after paramedics took him away in an ambulance and firefighters arrived on the scene looking to assist paramedics with CPR.

“Did you have any idea up to that point of the seriousness of the medical condition of Mr. Floyd?” Paule asked.

Thao answered, “I had no idea.”

“I kind of connected the dots … OK. I guess this guy was in critical condition when they left,” Thao said.

Under cross-examination from Assistant U.S. Attorney LeeAnn Bell, Thao acknowledged he was aware of Chauvin’s knee on Floyd’s neck, that Floyd had stopped talking and appeared to be unconscious. He also agreed that police are trained to immediately start CPR if someone loses a pulse and there are no paramedics around, and have a duty to intervene when they witness another cop committing a crime.

All three defendants 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.

ABC News’ Whitney Lloyd contributed to this report.