Prosecutors argue that former Minneapolis police officer Derek Chauvin killed George Floyd by pinning him facedown to the pavement for nine and a half minutes, which made it impossible for Floyd to get the oxygen he needed to stay alive. Although that account was reinforced last week by detailed testimony from Chicago pulmonologist Martin Tobin, it is complicated by Hennepin County Chief Medical Examiner Andrew Baker's autopsy report, which said nothing about asphyxia, instead attributing Floyd's death to "cardiopulmonary arrest complicating law enforcement subdual, restraint, and neck compression." But as Baker's testimony in Chauvin's murder trial on Friday demonstrated, this distinction matters less than Chauvin's defenders suggest.
Baker agreed with the defense that Floyd's heart disease and drug use, both of which were mentioned in the autopsy report, contributed to his death. But Baker said those factors were not "direct causes," and he reiterated his conclusion that Floyd would have survived the encounter, which happened after he was arrested for using a counterfeit $20 bill to buy cigarettes on May 25, if police had handled the situation differently. "I would still classify it as a homicide today," Baker said.
Baker said Floyd had an enlarged heart due to hypertension, meaning his heart would have required extra oxygen, and substantially narrowed coronary arteries, meaning they had "a limited ability to deliver" that oxygen to the heart. Floyd also had a low level of methamphetamine in his blood: 19 nanograms per milliliter, which prior testimony indicated is similar to what would be seen in someone who had taken a single prescribed dose of the drug. Without commenting specifically on how methamphetamine affected Floyd, Baker said, "My understanding is that methamphetamine is hard on the heart. It is going to increase heart rate. It is going to increase the work of the heart because it is a stimulant."
But even allowing for those "contributing causes," Baker said, his judgment remains that "law enforcement subdual, restraint, and neck compression" played a crucial role in Floyd's death, which is why he classified it as a homicide. "We apply the term homicide when the actions of other people were involved in an individual's death," he explained.
Baker noted that "cardiopulmonary arrest" is "really just fancy medical lingo for 'the heart and the lungs stopped'—no pulse, no breathing." He said the phrase "cardiopulmonary arrest complicating law enforcement subdual, restraint, and neck compression" means that Floyd's heart and lungs stopped functioning in that context. And that "top line" description, he noted, is "the most important thing that precipitated the death."
In Baker's view, the use of force against Floyd fatally interacted with his "very severe underlying heart disease." Here is how Baker described what he thinks happened:
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, that involves things like being held to the ground, that involves things like the pain that you would incur from having your cheek up against the asphalt and an abrasion on your shoulder, those events are going to cause stress hormones to pour out into your body….That adrenaline is…going to ask your heart to beat faster. It's going to ask your body for more oxygen so that you can get through that altercation. In my opinion, the law enforcement subdual, restraint, and the neck compression [were] just more than Mr. Floyd could take by virtue of those heart conditions.
As to whether breathing difficulty caused by the prolonged prone restraint made it even harder for Floyd to get the oxygen he needed, Baker said, "I would defer to a pulmonologist." Tobin has exactly the sort of expertise to which Baker alluded, and he concluded that "Floyd died from a low level of oxygen" caused by obstructed breathing, which ultimately "caused his heart to stop." Tobin said even a perfectly healthy person would have died in these circumstances.
Forensic pathologist Lindsey Thomas, who also testified on Friday, likewise attributed Floyd's death to inadequate breathing. "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," she said.
In all of these accounts, Chauvin's actions were the but-for cause of Floyd's death. Whether Floyd died because he could not breathe, as he repeatedly complained while he was pinned to the pavement, or because his heart could not handle the stress of this "altercation," as Baker suggests, the use of force was the crucial thing that killed him. Baker and the other medical experts agree on that point, even when they differ on the details.