MINNEAPOLIS — The chief county medical examiner who ruled George Floyd’s death a homicide testified Friday that the way police held him down and compressed his neck “was just more than Mr. Floyd could take,” given the condition of his heart.

Derek Chauvin

Dr. Andrew Baker, the Hennepin County medical examiner, took the stand at the murder trial of former Officer Derek Chauvin for pressing his knee on or close to Floyd’s neck for what prosecutors said was as much as 9 1/2 minutes as the 46-year-old Black man lay pinned to the pavement last May.

Baker concluded last year that Floyd died from cardiopulmonary arrest — that is, his heart stopped — complicated by the way police held him down.

When Baker was asked how police “subdual, restraint and neck compression” led to Floyd’s death, he said that Floyd had severe underlying heart disease and an enlarged heart that needed more oxygen than normal to function, as well as narrowing of two heart arteries.

Baker said being involved in a scuffle raises adrenaline, which asks the heart to beat even faster and supply more oxygen.

“And in my opinion, the law enforcement subdual, restraint and the neck compression was just more than Mr. Floyd could take by virtue of that, those heart conditions,” the medical examiner said.

Chauvin, 45, is charged with murder and manslaughter in Floyd’s death May 25. Floyd was arrested outside a neighborhood market after being accused of trying to pass a counterfeit $20 bill.

Bystander video of Floyd crying that he couldn’t breathe as onlookers yelled at the white officer to get off him sparked protests and scattered violence around the U.S.

Chauvin attorney Eric Nelson has argued that the now-fired white officer did what he was trained to do and was not responsible for Floyd’s death. Floyd had high blood pressure and heart disease, and an autopsy found fentanyl and methamphetamine in his system.

But the autopsy itself ruled out heart attack, aneurysm and other causes.

Baker testified that his examination of Floyd’s heart found no “visible or microscopic previous damage” to the heart muscle. Baker also said he noticed no injury to Floyd’s brain from either trauma or oxygen deprivation. And he said he did not notice any pills or pill fragments in Floyd’s stomach.

Other medical experts called as prosecution witnesses have likewise blamed Floyd’s death on the way he was pinned down on the ground.

Dr. Lindsey Thomas, a forensic pathologist who retired in 2017 from the Hennepin County Medical Examiner’s Office and did not work on Floyd’s case, testified earlier Friday that she agreed with Baker’s findings, but was even more explicit, saying the “primary mechanism of death” was asphyxia, or insufficient oxygen.

She said she reached that conclusion mostly from video that showed Floyd struggling to breathe.

“This is a death where both the heart and lungs stopped working. The point is, it’s due to law enforcement subdual, restraint and compression,” Thomas said. She said that there was nothing in Floyd’s autopsy that noted that, but she said that is not uncommon.

Baker said other significant conditions listed in the death certificate are things that played a role, but didn’t directly cause Floyd’s death.

“Mr. Floyd’s use of fentanyl did not cause the subdual or neck restraint. His heart disease did not cause the the subdual or the neck restraint,” he said.

Baker also said he did not watch the harrowing video of the arrest before examining Floyd so that he would not be influenced by what he saw.

“I was aware that at least one video had gone viral on the Internet, but I intentionally chose not to look at that until I had examined Mr. Floyd,” he said. “I did not want to bias my exam by going in with any preconceived notions that might lead me down one pathway or another.”

Under cross-examination by Nelson, Thomas said she believed Floyd’s heart was “slightly” enlarged.

Nelson asked Thomas about what could cause a heart to suddenly stop beating, noting that Floyd’s bigger heart needed more blood and was working hard in a moment of stress and adrenaline, and that one of his arteries had a 90% blockage.

Thomas said any blockage over 70% to 75% could be used to explain death, in the absence of another cause. But she also said some people can live just fine with an artery that is fully blocked.

The defense attorney pressed Thomas by posing a hypothetical question.

“Let’s assume you found Mr. Floyd dead in his residence. No police involvement, no drugs, right?. The only thing you found would be these facts about his heart. What would you conclude to be the cause of death?” Nelson asked.

“In that very narrow set of circumstances, I would probably conclude that the cause of death was his heart disease,” Thomas replied.

She also agreed that fentanyl can slow a person’s breathing and that methamphetamine can cause the heart to work harder and cause cardiac arrhythmia — a potentially lethal heart rhythm disturbance.

In response to another hypothetical posed by Nelson, she agreed that she would certify Floyd’s death as an overdose if there were no other explanations.

But during re-questioning, prosecutor Jerry Blackwell ridiculed the defense attorney’s hypotheticals and quickly got Thomas to repeat that the cause of Floyd’s death was the restraint by police.

“Aren’t those questions a lot like asking, ‘Mrs. Lincoln, if we take John Wilkes Booth out of this …,’” Blackwell began, before Nelson objected.

For the first time, a seat designated for Chauvin’s family was occupied Friday, by a woman. She wasn’t immediately identified. Chauvin’s marriage ended in divorce in the months after Floyd’s death.

Also on Friday, Judge Peter Cahill called in a juror and questioned her about whether she had been subject to any outside influences. She replied that she briefly saw TV coverage with the sound off and said that her mother-in-law had texted her, “Looks like it was a bad day” but that she didn’t reply.

The judge allowed her to remain on the jury.