Derek Chauvin trial: Witnesses questioned by lawyers

Three people who witnessed Chauvin kneeling on Floyd’s neck called 911 on the officers who were at the scene, Blackwell said.

A first responder, who was distressed that the officers were not checking Floyd’s pulse or performing chest compressions on him, called the police, Blackwell said.

Another man, who Blackwell described as a "very focal” bystander with a background in security and mixed martial arts, also called the police.

The third person was a 911 dispatcher who could see the encounter through a fixed police camera on the scene.

The incident was "so unusual, and for her, so disturbing," that she called a sergeant at the police department to alert him to what was happening, Blackwell said.

Blackwell played a portion of the 9 minute and 29 second video taken by a witness on May 25, 2020.

"For half of that time, Mr. Floyd was unconscious, breathless and pulseless," Blackwell said.

Blackwell said Floyd can be seen repeatedly heaving his right shoulder into the air. This move was an attempt by Floyd to expand his ribcage so he could breathe, as he was "pancaked" between the hard pavement beneath him and Chauvin on top of him, Blackwell said.

Chauvin watched intently as the video was played in the courtroom.

Derek Chauvin failed the responsibilities that come with the badge he was given by the Minneapolis Police Department when he pressed his knee on George Floyd’s neck and killed him, prosecutor Jerry Blackwell said in opening statements Monday.

Part of the oath Minneapolis police officers take is to enforce the law "courteously and appropriately," while “never employing unnecessary force,” Blackwell said, adding that Chauvin violated both when he engaged in the "grinding and crushing" of Floyd "until the very life was squeezed out of him."

"Mr. Chauvin betrayed his badge," Blackwell said.

Floyd was unarmed, in handcuffs and did not present a threat to anyone, Blackwell said.

"He was completely in the control of the police," Blackwell said. “He was defenseless.”

Blackwell vowed to give Chauvin a fair trial, but stated that he was "anything but innocent" on May 25, 2020 -- the day that Floyd died.

The prosecution plans to prove that Chauvin engaged in "force that he applied without the regard for its impact," Blackwell said.

The civil rights attorneys representing the family of George Floyd -- Benjamin Crump, Antonio Romanucci and L. Chris Stewart as well as the Rev. Al Sharpton -- spoke to reporters Monday morning.

“Today starts a landmark trial that will be a referendum on how far America has come in its quest for equality and justice for all,” Crump said, with Floyd’s family present.

Crump stressed that the evidence against Chauvin speaks for itself, saying this “murder case is not hard."

“We're not asking for anything extraordinary,” Crump said. “We're asking for equal justice under the law.”

ABC News’ Arielle Mitropoulos contributed to this report.