Dr. Lindsey Thomas, who has worked for 36 years as a forensic pathologist in medical examiners' offices, testified Friday in Chauvin's murder trial.
After reviewing Floyd's medical records, his autopsy report and the videos showing in great detail the circumstances of his death, she said she supports the Hennepin County medical examiner's conclusion that the manner of death was homicide — a finding that means Floyd died "at the hands of another," which is not in itself indicative of criminal guilt.
"What it means to me is that the activities of the law enforcement officers resulted in Mr. Floyd's death, and that specifically those activities were the subdual, the restraint and the neck compression," Thomas said. "The primary mechanism was asphyxia or low oxygen. Mr. Floyd was in a position — because of the subdual restraint and compression — where he was unable to get enough oxygen in to maintain his body functions."
The murder charges against Chauvin became international news last spring, after millions of people viewed a bystander's video of Floyd's arrest. It showed Chauvin pinning Floyd's neck down for about nine minutes, as Floyd — who was suspected of using a counterfeit $20 bill — begged him to stop, said he couldn't breathe and eventually lost consciousness.
The video of a Black man gasping for breath under the knee of a white police officer sparked historic nationwide demonstrations for racial justice that lasted through the summer.
The footage, along with security camera tapes and videos from the officers' body-worn cameras, were also key to Thomas' findings about Floyd's death. Though she's testified in about 100 trials, she said she'd "never had a case like this with such thorough documentation of the terminal event."
"The evidence from the terminal events, the videos, show Mr. Floyd in a position where he was unable to breathe," she told Jerry Blackwell of the Minneapolis law firm Blackwell Burke, who is working pro bono for the prosecution.
The video also helped rule out other potential causes of death, she said. Floyd's blood tested positive for fentanyl and methamphetamine, but Thomas said that before and during his encounter with police, Floyd didn't display signs of an overdose — sleepiness and painlessly slipping into a coma. On the contrary, he was alert and sensitive to pain.
The video also ruled out what Blackwell called a "lights-out sudden death," which would occur in the case of an arrhythmia or sudden stopping of the heart.
"There was nothing sudden about his death," she said.
The autopsy helped rule out a cardiac event as well, she said, because it showed no signs of muscle damage or scarring of Floyd's heart. Floyd's body showed no indications of underlying lung disease or stroke, either.
On cross-examination, Chauvin's attorney, Eric Nelson of Halberg Criminal Defense, noted that Floyd's heart was enlarged and that his medical records indicated he had a history of high blood pressure. Floyd's coronary arteries were narrowed — the blockage, which was found to be 70-90%, was above the 70% occlusion threshold that Thomas said "in the absence of another cause could be used to explain death."
Nelson also brought up Thomas' testimony on the physiological stress that Floyd was under during his arrest — a fight-or-flight response that can trigger a surge of adrenaline. That, Nelson noted, could make the heart work harder.
"Let's take the police out of this," he said. "Say you found Mr. Floyd in his residence. No police involvement, no drugs. The only thing you found would be these facts about his heart. What would you conclude to be the cause of his death?"
"In that very narrow set of circumstances, I would probably conclude that the cause of death was his heart disease," Thomas conceded.
She similarly testified that had police not been involved and if Floyd's heart were in good condition, she could have found he died of a drug overdose based on the amount of fentanyl in his system.
On redirect, Blackwell tried to point out a possible fallacy in that questioning, likening it to "asking Mrs. Lincoln, if not for John Wilkes Booth ..."
But Judge Peter Cahill cut him off, saying his question was argumentative.
Jurors also heard testimony from Dr. Andrew Baker, chief medical examiner for Hennepin County, who performed Floyd's autopsy and described it in graphic detail.
Baker seemed to take a more nuanced approach to his findings than Thomas did, noting that because of the size and blockage of Floyd's heart, it "already need[ed] more oxygen than a normal heart." That, combined with the strain and pain of being restrained by police, caused Floyd's body to release stress hormones, Baker said.
"What that adrenaline is going to do is, it's going to ask your heart to beat faster, it's going to ask your body for more oxygen so you can get through that altercation and, in my opinion, the law enforcement subdual, restraint and neck compression was more than Mr. Floyd could take," he said.
--Editing by Philip Shea.
Update: This story has been updated to include coverage of Andrew Baker's testimony.
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