Day 22 of Derek Chauvin trial: Medical examiner who did autopsy did not include a lack of oxygen

The medical examiner who did the autopsy on George Floyd testified Friday that because of underlying heart conditions, his restraint by police "was just more than Mr. Floyd could take," resulting in his death while held down on the street at a Minneapolis intersection.

Soon after Floyd's arrest on May 25, Dr. Andrew Baker ruled that Floyd's cause of death in at 38th and Chicago was "cardiopulmonary arrest complicating law enforcement subdual, restraint, and neck compression."

Baker did not include a lack of oxygen, or asphyxia, a cause that three medical expert witnesses has firmly said was what killed Floyd after being pinned on his stomach under the ex-police officer Derek Chauvin's knee for more than nine minutes.

Cause of death has provided a sharp divide between the state and the defense. Chauvin's attorney, Eric Nelson, has argued that Floyd died of a cardiac arrest, illicit drug use and various chronic health problems.

After differences arose in earlier testimony and during questions from Nelson about Floyd's diseased heart and use of potentially deadly drugs, Baker stood firmly behind his initial ruling on direct cause of death.

"My opinion remains unchanged," Baker said as his testimony concluded. "That was my top line then, [and] it would remain my top line now."

He affirmed his findings about Floyd's health problems and drugs, saying again "those are not direct causes. Those are contributing causes."

Judge Peter Cahill adjourned for the day after Baker was dismissed and said the trial would resume Monday about 9:30 a.m. with another medical expert for the prosecution.

Earlier Friday, Baker said that "to the best of my knowledge [Floyd] was generally healthy on May 25 before the events of that evening."

That said, the doctor tied in the somewhat diseased condition of the 46-year-old Floyd's heart to his death.

"You know he had very severe underlying heart disease," Baker said. "Mr. Floyd also had what we call hypertensive heart disease, meaning his heart weighed more than it should. So he has a heart that already needs more oxygen than a normal heart by virtue of its size, and it's limited in its ability to step up to provide more oxygen when there's demand because of the narrowing of his coronary arteries.

"Now, in the context of an altercation with other people that involves things like physical restraint, it involves things like being held to the ground, it involves things like the pain that you would incur from having your cheek up against the asphalt and that abrasion on your shoulder, those events are gonna cause stress hormones to pour out of your body, specifically things like adrenaline — and what that adrenaline is going to do is it's going to ask your heart to beat faster," Baker testified.

"It's going to ask your body for more oxygen so that you can get through that altercation, and in my opinion, the law enforcement subdual restraint and the neck compression was just more than Mr. Floyd could take by virtue of those heart conditions."

While earlier medical expert testimony doubted that Floyd's physical condition or his illicit drug use played a role in the death, Baker said under questioning by defense attorney Nelson that "in my opinion, yes," they were factors.

As he has done throughout the trial, Nelson raised doubt about the other experts discounting the role of the fentanyl found in Floyd's body during Baker's autopsy.

Nelson had Baker disclose what he told prosecutors earlier about whether Floyd overdosed, and Baker replied, "I don't recall specifically what I told the county attorney, but it almost certainly went something like this: Had Mr. Floyd been home alone in his locked residence with no evidence of trauma, and the only autopsy finding was that fentanyl level, then yes, I would certify his death as due to fentanyl toxicity. But again, interpretation of drug concentration is very context-dependent."

Nelson also returned to a line of questioning about bruising on the neck of someone who dies of asphyxia from strangulation.

"In my world, we typically see bruises on the neck and abrasions on the neck," Baker said, who added that he saw no bruises or scrapes on Floyd's neck.

Asked by Nelson about whether Floyd died of strangulation. Baker said: "That's something we don't really see, pressure to the back of the neck resulting in strangulation."

"Or asphyxiation?" Nelson asked.

Baker confirmed that's correct. He also agreed with Nelson that pressure on the side of the neck, which occurred for much of the time Floyd was on the pavement under Chauvin's knee, would not constrict his airway.

Baker testified that his autopsy on Floyd's heart revealed no previous damage to the heart muscle. However, blockage from cholesterol and scarring left his heart arteries "pretty severely narrowed," estimated in some locations at 75 to 90%. Inspection of the brain and lungs found nothing out of the ordinary.

The doctor began his testimony by saying, "I was aware that Mr. Floyd had become unconscious while he was in police custody" and died at the hospital. He opted not to look at videos of Floyd's death, including the one that went viral online, so as not to be biased in his findings.

"In general," he explained, "I don't wan to go into autopsies with a preconceived notion about what already happened. It might cause me to skip something."

Baker was shown photos he took from the autopsy and also distributed to the jury and others in the courtroom but out of the view of the global livestream audience.

The doctor said one photo showed bruises and scrapes to his left eyebrow area. He said Floyd suffered those injuries while "being pinned against the asphalt the night before."

"In the prone position?" prosecutor Jerry Blackwell said. "Yes," the doctor responded.

Baker then went on to go through other photos of other injuries to Floyd, again repeating much the same conclusion about the source of the wounds.

Friday morning, one of the experts who testified on behalf of the prosecution was Dr. Lindsey Thomas, a veteran medical examiner who worked on Baker's staff from 2013 to 2017 and considers him a friend.

"In this case, I believe the primary mechanism of death is asphyxia, or low oxygen," said Thomas, a medical examiner of 37 years who retired from the Hennepin County Medical Examiner's Office and still works part-time as a forensic pathologist in Reno and Salt Lake City.

Thomas explained that although Floyd's heart stopped, he didn't die from a heart attack.

"The activities of the law enforcement officers resulted in Mr. Floyd's death, and specifically those activities were the subdual restraint and the neck compression," she said.

She said the sheer volume of videos of Floyd's death was "absolutely unique" in that she'd never had a case so thoroughly documented, and it helped her arrive to determine how Floyd died.

"What I observed from all of these videos is this was not a sudden death," Thomas testified. "It's not like snow shoveling when someone clutches their chest and falls over. There was nothing sudden about his death."

She later said with certainty, "There's no evidence to suggest he would have died that night except for the interactions with law enforcement."

Thomas said she agreed with Baker's determination on the cause of death. However, Thomas's declaration runs counter to Baker's assessment that he could not say whether Floyd would have lived "but for" the officers' use of force, according to documents obtained in the case.

"Baker did not believe that the prone position was any more dangerous than other positions based on an article or journal he had read," said a summary of the meeting. He repeated that viewpoint in his testimony Friday.

Thomas also joined other expert witnesses before her saying illicit drug use did not kill Floyd.

Prosecutor Blackwell spent a fair amount of time having Thomas explain some of the limitations of an autopsy and what advantages she had in her research of Floyd's death.

She zeroed in on why Floyd's health challenges and drug use were included by Baker and explained that such information is valuable for a "public health purpose" and not considered a direct cause of death.

"In any given case, we aren't just thinking of this particular person," Thomas said. "[Autopsy results] list disease processes or drugs that are present at the time of death, but we don't believe they directly contributed to the cause of death."

She also downplayed the autopsy failing to mention lack of oxygen, or asphyxia, despite she and others who have testified to this being the direct cause of death.

"I tend not to use it," she said, while also pointing out that there is no test during an autopsy to detect this cause. As an example, Thomas said, "I wouldn't say asphyxia during hanging. I would just say hanging."

She revisited ground covered by previous medical expert witnesses concerning injuries on Floyd's body that revealed his struggle to reposition himself to allow him to better breathe: scrapes on his knuckles, face and shoulders, for example.

Thomas testified that she wasn't being paid for her time reviewing evidence and testifying. "You reached out to me, and I knew this was going to be important, and I felt like I had something to offer, and I wanted to do what I could to explain what I think happened," she said.

Thomas testified that the bodily stress of being restrained in a prone position must be taken into account.

"Mr. Floyd was already in a position where he was not experiencing breathing [nor] getting enough oxygen in this body," she said. "On top of that, now there's the physiological stress that's putting increased demand on his heart, lungs and muscles. ... He's using his strength to get himself into a position where he can breathe."

Add in the release of adrenaline, rapid breathing and other bodily reactions, she said, "it's kind of a double whammy to his heart, lungs, his muscles and his whole system."

In cross examination by defense attorney Nelson, Thomas acknowledged that Floyd had a slightly enlarged heart that would require more blood and significantly narrowed arteries.

With those factors, along with the stress Floyd endured, "the heart has to work very, very hard in this case, right?" Nelson asked.

"Let's take the police out of this," Nelson continued. "Let's assume you found Mr. Floyd dead in his residence, no police involvement, no drugs, the only thing you found were these facts about his heart. What would you conclude is the cause of death?"

"In those very narrow circumstances, I would probably conclude that the cause of death was his heart disease," Thomas said.

Nelson revived his earlier questioning of witnesses pointing out to Thomas the lack of bruising on Floyd's neck or elsewhere and how fentanyl and meth can be fatal, even in small amounts. Thomas agreed, but with qualified answers such as "it can" or there being numerous variables to consider.

Nelson said that when someone is in cardiac arrest and given a saline solution intravenously — as occurred in Floyd's case — that procedure can decrease the amount of controlled substances that would be measured in the body.

Thomas called that "a theoretical possibility."

Blackwell rose again and took aim at Nelson's scenario minus the police.

"Aren't those questions a lot like asking, 'Mrs. Lincoln, if we take John Wilkes Booth out of this ...' " before Nelson objected and the judge sustained and explained the incomplete question was argumentative."

Chauvin for the first time had a spectator in the courtroom, an unidentified woman who sat in the family representative seat.

Staff writer Libor Jany contributed to this report.