The professional mixed martial arts fighter happened onto the scene when he went to the Cup Foods store in South Minneapolis where officers arrested George Floyd. When he saw Chauvin kneeling on Floyd’s neck, he loudly protested and began to record what happened. In court he described what he saw as a “blood choke” maneuver used to subdue an opponent.
"I believe I witnessed a murder,” he told Assistant Minnesota Attorney General Matthew Frank. “I felt the need to call the police on the police.”

A high school senior at the time she witnessed the incident, she posted video of Floyd’s arrest on Facebook and it went viral, shocking the world at the images of police misconduct, which ultimately led to a murder conviction. On the witness stand her face wasn’t shown but her voice was heard describing what she saw.
"I heard George Floyd say, 'I can't breathe. Please get off me,” she said. “It seemed like he knew it was over for him. He was suffering."

The Minneapolis firefighter was off duty that day and was on the corner where George Floyd’s arrest took place. She tried to tell responding officer Tou Thao that she had emergency medical training and that she could help Floyd. But apparently he did not believe her and ordered her back with other onlookers onto the sidewalk.
She testified that she knew Floyd was in distress because of the “puffy and swollen” appearance of his face, “which would happen if you are putting a grown man’s weight on someone’s neck,” referring to Chauvin.

The head of the Minneapolis Police Department had fired Chauvin and the three other responding officers at the scene days after Floyd died. He said that de-escalation tactics were not followed as directed and the amount of force used was not necessary to subdue him.  He testified that Chauvin violated department policy and went beyond his training when he placed his knee on Floyd’s neck.
"Once Mr. Floyd had stopped resisting — and certainly once he was in distress and trying to verbalize that — that should have stopped," Arradondo said. "It is my firm belief that the one singular incident we will be judged forever on will be our use of force. While it is absolutely imperative that our officers go home at the end of their shift, we want to make sure our community members do too."

One of the nation’s leading experts on pulmonology, Tobin researched the evidence in the case and found that Floyd’s normal breathing was stopped because of Chauvin’s positioning of his knee on the suspect’s neck, which he described as severely cutting off Floyd’s air passages to the point where Floyd had to writhe on the ground and even try to push himself up by his knuckle in an attempt to get air.

"To most people, this doesn't look terribly significant, but to a physiologist this is extraordinarily significant, because this shows he has used up all his resources and showed he is trying to breathe with his fingers and knuckles," Tobin explained.

The Hennepin County Medical Examiner performed the autopsy on Floyd just a day after he was pronounced dead. He ruled Floyd’s death a homicide and concluded Floyd died of “cardiopulmonary arrest complicating law enforcement subdual, restraint, and neck compression." Essentially that meant Chauvin’s knee to neck tactic caused the termination of Floyd’s life.

Although the defense tried to maintain that drugs found in Floyd’s system and a heart condition contributed to his death as much as other factors, Baker would not move off of his original finding: “The law enforcement subdual, restraint and the neck compression was just more than Mr. Floyd could take by virtue of those heart conditions,” he said.

Much of the Chauvin defense strategy centered on convincing jurors that there were other outlying factors that were the cause of Floyd’s death, and not just the officer’s tactics. So attorney Eric Nelson called Fowler, the former chief medical examiner for the state of Maryland, to examine the evidence. His analysis of Floyd’s death led him to conclude that he died of a cardiac arrhythmia brought on by heart disease, rather than direct police restraint.
"There are multiple entities acting with each other and adding to each other," he said under questioning.
However, special prosecutor Jerry Blackwell cross examined Fowler, poking holes in that theory. “Every one of us in this room will have a fatal arrhythmia at some point, because that’s kind of how you go, right?” To which Fowler agreed.