What Was the Cause of George Floyd’s Death? Autopsies and Testimony

The cause of George Floyd’s death, as recorded by the Hennepin County Medical Examiner, was “cardiopulmonary arrest complicating law enforcement subdual, restraint, and neck compression,” and the manner of death was ruled a homicide.¹ In plain language, Floyd’s heart and lungs stopped working because Minneapolis police officers held him face-down on the pavement and compressed his neck for more than nine minutes on May 25, 2020. Every prosecution medical expert who later testified at Derek Chauvin’s murder trial reached the same core conclusion: Floyd died from a lack of oxygen caused by the restraint.

What the Official Autopsy Found

Dr. Andrew Baker, the Hennepin County Medical Examiner, performed the autopsy and signed the death certificate in June 2020. He gave the death two components. The direct cause was cardiopulmonary arrest brought on by the police restraint and neck compression. Contributing but not causal were “other significant conditions”: arteriosclerotic and hypertensive heart disease, fentanyl intoxication, and recent methamphetamine use.¹

At trial, Baker explained the distinction under oath. The restraint and neck compression were the direct cause; the heart disease and drugs were background conditions that made Floyd more vulnerable to what the officers were doing. In his words, “the law enforcement subdual, restraint and the neck compression was just more than Mr. Floyd could take, by virtue of those heart conditions.”² Baker also stated directly that Floyd’s drug use did not cause the restraint and his heart disease did not cause the restraint. Asked whether his opinion had shifted since he signed the death certificate, he said it had not.³

The Independent Autopsy

Floyd’s family commissioned a second autopsy conducted by Dr. Michael Baden, a former New York City chief medical examiner, and Dr. Allecia Wilson of the University of Michigan. They concluded Floyd died of “asphyxia due to neck and back compression that led to a lack of blood flow to the brain.” They too classified the manner of death as homicide.⁴

The two autopsies agreed on the manner of death and both identified the restraint as the cause. They used different language for the mechanism. The official autopsy described the heart and lungs stopping under the physical stress of restraint; the independent examiners described mechanical asphyxiation from pressure on the neck and back. Dr. Wilson also said the toxicology results and underlying health conditions would “not change or alter the cause of death with mechanical asphyxia.”⁴

How the Restraint Killed Him

At Chauvin’s 2021 trial, four medical specialists walked the jury through the physical process. Their accounts converged on the same finding: Floyd’s body was deprived of oxygen until his brain and heart failed.

The Pulmonologist

Dr. Martin Tobin, a pulmonologist and critical care specialist, identified four forces acting on Floyd’s body at the same time: his prone position on the street, handcuffs pulling his arms behind his back, a knee on his neck, and a knee on his back and side. Together they compressed him between the asphalt and the officers’ weight, leaving his left lung “almost entirely unable to operate.”⁵

Tobin used precise numbers to rule out a drug explanation. Shortly before Floyd lost consciousness, his breathing rate was 22 breaths per minute, within the normal range of 12 to 22. If fentanyl had been depressing his breathing, Tobin said, the rate would have dropped to about 10. The measured rate was instead consistent with someone straining against a narrowing airway.⁶ He identified the moment of brain injury just after the five-minute mark of the restraint, when an involuntary leg extension visible on video signaled seizure activity from oxygen loss. Floyd’s last breath came at 8:25 p.m. Tobin concluded the oxygen deprivation caused brain damage and triggered a fatal heart rhythm called pulseless electrical activity. His summary: “A healthy person subjected to what Mr. Floyd was subjected to would have died.”⁵

The Forensic Pathologist

Dr. Lindsey Thomas told the jury the “primary mechanism of death is asphyxia or low oxygen” and that “there’s no evidence to suggest he would have died that night except for the interactions with law enforcement.”⁷ She rejected a drug overdose as the cause. Fentanyl deaths, she explained, are typically slow and peaceful, and the video showed nothing of the kind.

The Police Surgeon

Dr. Bill Smock, a forensic medicine specialist, testified that Floyd died of “positional asphyxia” — a lack of oxygen caused by the position of his body. Smock went through the alternative theories one by one and ruled each out: no fentanyl overdose, no methamphetamine overdose, no heart attack, no excited delirium. He pointed to Floyd’s words on the video. “He’s breathing. He’s talking. He’s not snoring. He is saying, ‘Please, please get off of me. I want to breathe. I can’t breathe.’ That is not a fentanyl overdose. That is somebody begging to breathe.”⁸

The Cardiologist

Dr. Jonathan Rich testified that Floyd had “an exceptionally strong heart” and stated “with a high degree of medical certainty” that Floyd “did not die from a primary cardiac event and did not die from a drug overdose.” He attributed the death to low oxygen from the restraint position and called it “absolutely preventable.”⁹

What Role Drugs and Heart Disease Played

Floyd’s toxicology report showed fentanyl at 11 nanograms per milliliter and methamphetamine at 19 nanograms per milliliter in his blood. Forensic toxicologist Dr. Daniel Isenschmid testified that these levels were “significantly lower than the average amount seen in blood samples of DUI suspects, and much lower than post-mortem cases for individuals who die from drug overdoses.”⁸

Floyd also had real cardiovascular disease. His heart was enlarged from hypertension, and two coronary arteries were significantly narrowed. Under cross-examination, Baker acknowledged these conditions and the drugs “played a role,” but he held to his classification of them as contributing conditions rather than direct causes.² The distinction is the point. The heart disease and fentanyl made Floyd less resilient to what was done to him. They did not, in the medical examiner’s assessment, cause his death, and they did not cause the officers to restrain him.

The Defense Theory and Why It Failed

Chauvin’s defense called Dr. David Fowler, the former chief medical examiner of Maryland. Fowler testified that Floyd died of a “sudden cardiac arrhythmia” caused by underlying heart disease combined with the drugs in his system, the stress of the arrest, and possibly carbon monoxide from a nearby squad car’s exhaust. He argued the manner of death should have been classified as “undetermined” and said Chauvin’s knee was “nowhere close” to Floyd’s airway.¹⁰

On cross-examination, prosecutor Jerry Blackwell dismantled the theory piece by piece. Fowler agreed that a person dying of oxygen deprivation ultimately dies of a fatal arrhythmia, which meant arrhythmia did not point away from asphyxia. On carbon monoxide, Blackwell established that Floyd’s blood had never been tested for it, that the squad car was a gas-electric hybrid, and that no one knew if the engine was even running; Fowler conceded he had no data.¹⁰ Fowler had also not accounted for the weight of Chauvin’s police gear in his pressure analysis. He agreed that Floyd might have been saved with immediate medical attention when he went into cardiac arrest.¹¹ The jury convicted Chauvin on all counts.

Misinformation About What Killed Him

Claims that Floyd actually died of a drug overdose or a heart attack continue to circulate on social media. Fact-checkers have repeatedly rebutted them, and the record does not support them.¹² The autopsy findings have not changed since June 2020. The medical examiner reaffirmed them under oath. Four independent medical specialists — a pulmonologist, a forensic pathologist, a forensic medicine specialist, and a cardiologist — testified for the prosecution that the restraint caused the death. Toxicology showed drug levels far below those found in overdose deaths, and a cardiologist testified that Floyd’s heart was strong. The one medical witness who offered an alternative explanation could not defend it under cross-examination. What killed George Floyd, on the evidence heard in court and recorded by the medical examiner, was the compression of his neck and body during a police restraint that lasted more than nine minutes.

1
Hennepin County Medical Examiner. Hennepin County Medical Examiner Press Release, Case 2020-3700
2
NPR. Medical Examiner Testifies About George Floyd’s Death
3
PBS NewsHour. Medical Examiner Doubles Down on Original Autopsy Finding
4
ABC News. Independent Autopsy of George Floyd Findings Announced
5
NPR. Chauvin Trial: Medical Expert Says George Floyd Died From a Lack of Oxygen
6
Rev. Pulmonologist Martin Tobin Testimony Transcript
7
CNN. Derek Chauvin Trial Day 10
8
ABC News. Medical Witnesses Clash Over George Floyd’s Death
9
The New York Times. Jonathan Rich Cardiologist George Floyd Death
10
Los Angeles Times. Expert Blames George Floyd’s Death on Heart Rhythm Problem
11
WBAL-TV. Derek Chauvin Trial April 14
12
FactCheck.org. George Floyd