Editor’s Note: See our coverage of the first day of the trial here, the second day here, and the third day here, the fourth day here, the fifth day here, the sixth day here, the seventh day here, the eighth day here, and the ninth day here.
The first witness called was Lindsey Thomas, a forensic pathologist. She described forensic pathology as “where medicine and the law meet.” Dr. Thomas works on unexpected and suspicious deaths; she is qualified to determine causes of death. She said that pathologists investigate a patient’s history, run laboratory tests, and look at what was going on at the time of death. Her job is to take information from both the body and the events around the death to find its cause. The state of Minnesota reached out to her for this trial and she did not charge a fee for her testimony.
She reviewed the medical examiner’s report, Floyd’s medical records, interviews, medical literature, and videos. “The use of videos is unique in this case,” she said. “There has never been a case that I worked on that used so many videos from so many different perspectives.” Dr. Thomas’s conclusion was that the primary reason for George Floyd’s death was “asphyxia.” In layman’s terms: low oxygen.
Prosecutor Jerry Blackwell led her through the information on the death certificate. The cause of death has different sections: “Immediate,” “Underlying,” and “Other Contributing Conditions.” George Floyd’s immediate cause of death is: “Cardiopulmonary arrest complicating law enforcement subdual, restraint and neck compression.” When asked to explain “cardiopulmonary arrest,” Dr. Thomas said that everyone dies when his heart stops. This does not mean that Floyd died of a heart attack or fatal arrhythmia. On “complicating law enforcement subdual, restraint and neck compression,” Dr. Thomas said, “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.” She said her own conclusion matches that of the medical examiner, Dr. Andrew Baker, whom she used to work with.
Mr. Blackwell asked Dr. Thomas to elaborate on the “mechanism of death.” She gave the example that with a gunshot wound, the mechanism would be blood loss. In Floyd’s case, she said, “The primary mechanism was asphyxia or low oxygen . . . He was unable to get enough oxygen in, to maintain his body functions.” She went on to say that after reviewing the video of his arrest, she concluded that Floyd’s bellows (“the system comprising the diaphragm and thorax”) malfunctioned because of the physical position the police put him in for an extended period of time. She noticed that Floyd had an “anoxic seizure,” an involuntary twitch of the body that indicates that the brain is not getting enough oxygen.
The doctor said that for a forensic pathologist, an autopsy is helpful for ruling things out. For instance, Floyd had Covid-19, but the autopsy showed that his lungs were not diseased. Floyd had no blood clots or ruptured blood vessels in the brain. A heart attack was ruled out because a recent heart attack would have shown damage in the heart muscle. Prior heart attacks would have shown scarring. “This was not a sudden death,” she said. The autopsy did not show signs of fatal heart arrhythmia. Her examination of the video evidence also led her to rule out Fentanyl overdose as the cause of death, as people who overdose become very sleepy.
On Floyd’s death certificate, “Underlying Conditions” was left blank, and “Other Contributing Conditions” were listed as, “Arteriorsclerotic and hypertensive heart disease; Fentanyl intoxication; recent methamphetamine use.” Dr. Thomas said she considered whether the “other contributing conditions” could have been the “immediate” cause of death. She ruled out methamphetamine as an “immediate” cause because meth overdoses are very sudden, causing a full-blown seizure, not like the minor twitch she observed in the video. When asked what “Underlying Conditions” meant, the doctor said those are the sequence of events that leads to a death. For example, an elderly person falls and breaks a hip, then goes to a hospital for surgery, where he then gets pneumonia.
The jury received autopsy photos in a packet. As they looked through them, Dr. Thomas explained that the superficial injuries on Floyd’s face, shoulders, wrists, and knuckles supported what they saw in the videos of Floyd’s arrest. Since he was being restrained, Floyd had to rub his face against the concrete ground, pull against his handcuffs, push with his shoulder, and push with his knuckles, to try to get into a position where he could breathe. She told the jury she did not think there was any evidence that Floyd would have died that evening without the actions of law enforcement. Her argument echoed what Prosecutor Jerry Blackwell told jurors on the first day of the trial: “You can believe your eyes.”
Mr. Blackwell asked her to discuss physiological stress. Dr. Thomas gave the example of the elevated stress a driver feels after narrowly avoiding a serious car accident and the way a mother feels when she loses track of her toddler at the beach. In Floyd’s case, the elevated stress lasted nine minutes. This chemical stress in Floyd’s body, in combination with everything else that was going on, made for a “double whammy” against his nervous system. The doctor explained that there are five possible choices for “manner of death”: natural, accident, suicide, homicide, and undetermined. Floyd’s death certificate states that the manner of death was “homicide.”
Dr. Thomas was asked about a study (Chan, et al.) of various restraint positions that concluded, “the restraint position resulted in a restrictive pulmonary function pattern but did not result in clinically relevant changes in oxygenation or ventilation.” She said that “in laboratory safe settings,” studies can show that the prone position is not harmful, but they “have no relevance to real world situations.” The studies use volunteers who have agreed to be in this position for the experiment, and they know that they can end the restraint at any time if they feel scared or uncomfortable — meaning there’s never any physiological stress. Dr. Thomas did not find the study relevant in determining George Floyd’s cause of death. Mr. Blackwell’s last question for her was about whether a healthy person would have died under the same circumstances. Dr. Thomas avoided a yes-or-no answer and said, “I wouldn’t want to be put in that position.”
Eric Nelson, Derek Chauvin’s lawyer, started his cross-examination by asking Dr. Thomas to explain what “complicating” means on George Floyd’s death certificate. She said that it meant “both things were present,” referring to Floyd’s heart stopping and the compression put on him by the police. Mr. Nelson then focused his questions on Floyd’s health. “Let’s talk about Mr. Floyd’s heart first,” he said. Dr. Thomas said Floyd’s heart, at 540 grams, was “slightly enlarged.” She said that 250 to 510 grams would be the normal range for someone of Mr. Floyd’s height. The primary cause of an enlarged heart is high blood pressure, and she acknowledged that Floyd had high blood pressure. An enlarged heart needs more blood and oxygen to function than a healthy one. Floyd had a 90 percent blockage in his right coronary artery and a 75 percent blockage in his left artery. Mr. Nelson asked Dr. Thomas, if — knowing these facts — she would have concluded that Floyd died of heart disease, had his body been found at home. She said yes, and that she had certified deaths of that nature before.
Mr. Nelson then asked if some of Floyd’s abrasions could have happened when Floyd was first put down on the ground, but Dr. Thomas wouldn’t give a straight answer. Next, he asked her about an article from the Journal of Forensic and Legal Medicine called “Incidence and outcome of prone positioning following police use of force in a prospective, consecutive cohort of subjects.” The doctor asked, “Was that the Canadian study?”
Mr. Nelson discussed the study, which was in fact Canadian. It was not conducted in a controlled laboratory environment, but was an analysis of actual police encounters, and real-life variables were considered. Out of over 1,000 arrests in which the suspects were placed in the prone position, there were no deaths. “Isn’t that amazing!?” Dr. Thomas exclaimed. “When you consider that virtually every forensic pathologist in the United States has probably had an officer involved in a death like this . . . It utterly baffles me, which is why I kept saying Canada, because I don’t know what’s different.”
When they moved on to the topic of drugs, Dr. Thomas said there is no safe amount of methamphetamine and it can increase the heart rate. She was aware that Floyd had likely ingested “speedballs,” a combination of Fentanyl and methamphetamine, before he died. She also said that some controlled substances affect the ability to breathe, which leads to low oxygen. Mr. Nelson presented her with a hypothetical situation in which a person is found at home after having ingested as much Fentanyl as Floyd had the day he died. Mr. Nelson asked if she would consider this an overdose, and she said she would.
On redirect, Mr. Blackwell started to say that Mr. Nelson’s questioning was like asking Lincoln’s wife if her husband would have died had he not been shot. This was objected to as argumentative, and Mr. Blackwell had to rephrase. Dr. Thomas seemed to agree that the hypothetical questions were not useful. She told Mr. Blackwell that she needed only pertinent information to make a decision about cause of death. Mr. Blackwell asked if there was any indication that Floyd had suffered sudden fatal arrhythmia or a heart attack. She said no. Mr. Blackwell asked if Floyd’s heart had been so “ordinary” in terms of injury that the medical examiner had chosen not to photograph it intact. Dr. Thomas replied that that was true: The heart had no scars or acute injury.
Regarding the Canadian study, Mr. Blackwell asked if there were studies with the same conclusions in America, and Dr. Thomas said no. “What is so peculiar about Canada that we’re talking about Canadian studies here?” Blackwell asked. “That’s what I don’t understand,” Dr. Thomas said, shrugging and shaking her head. “I don’t, I mean, yeah. I found that study and I thought, I don’t know how to interpret this. It’s so contrary to the actual experience of forensic pathologists in the United States.”
On redirect, Mr. Nelson asked Dr. Thomas if meth constricts the arteries. Then he asked, “Would you as a physician prescribe methamphetamine to a person who has a seventy percent to ninety percent occlusion in his or her heart?” Dr. Thomas smiled as Mr. Blackwell objected. Judge Peter Cahill said she could answer if she had an opinion. She didn’t.
After the lunch break, Dr. Andrew Baker, the medical examiner who conducted the autopsy on George Floyd, was sworn in. He is the chief medical examiner for Hennepin County. Dr. Baker said he conducted a “robust data set,” which meant that the autopsy was more detailed than usual. Extra photographs were taken, and there were extra notes on what was found and not found. He did this because it was likely that there could be a trial concerning Floyd’s death. The doctor did two things for Floyd that are not part of a typical autopsy: 1) He made incisions around Floyd’s wrists to look under the skin, and 2) He looked under the skin on Floyd’s back to see if there was fresh bruising.
The jury went through their packet of autopsy photos again, this time with Dr. Baker explaining things as they went. There were no injuries to Floyd’s back, but there were several injuries to his face and shoulder, which were consistent with Floyd getting scraped on asphalt. The doctor said that the blunt force injuries on Floyd’s knuckles could have been either from fighting with the police or from banging into the asphalt.
Dr. Baker said he hadn’t taken a picture of the heart intact because it appeared to be normal. The heart was found to be enlarged later on, only after weighing it, but this would not have been apparent in a photograph. He found no visible or microscopic damage to the heart. The doctor said plaque buildup caused two arteries to be 75 percent blocked. A careful dissection of the heart revealed no damage that would have killed Floyd.
The medical examiner also found nothing wrong with Floyd’s brain, other than that it had been deprived of oxygen. Floyd had a lot of fluid and congestion in his lungs, but Dr. Baker said this could have happened for several different reasons. There were no pulmonary emboli, and the doctor didn’t see any evidence of Covid-19. Dr. Baker found no pills in Floyd’s stomach, either. He did not send the stomach fluid to be analyzed.
Dr. Baker did find a paraganglioma tumor in Floyd’s pelvis, but didn’t think it had anything to do with Floyd’s death. He ordered a toxicology screen to look for both prescription and illegal drugs. Dr. Daniel Isenschmid, who testified in court on Thursday, did all the toxicology screening. Dr. Baker also said that Floyd had asymptomatic sickle cell trait. Floyd’s blood sickled when examined after death, but there was no evidence that his blood was sickling when he was alive.
When asked about the manner of death, Dr. Baker said that medical examiners only get involved when the cause of death does not seem natural. He said “homicide” means that the actions of other people are involved in the person’s death, and he emphasized that on a death certificate, it is a medical term, not a legal term.
Mr. Blackwell asked why the doctor had not mentioned drugs on the top line of the death certificate. Dr. Baker said the drugs “may have contributed, but were not the cause” of death. Defining his top line cause of death, the doctor said “cardiopulmonary arrest” is just a fancy medical term that means the heart and lungs stopped. “Complicating” means “occurring at the setting of.” On “subdual restraint and neck compression,” the doctor said that Floyd had hypertensive heart disease. “In the context of an altercation with other people, those events pour adrenalin out to ask the body for more oxygen,” Dr. Baker said, adding that it was “just more than Mr. Floyd could take, by virtue of those heart conditions.”
During the cross-examination, Mr. Nelson asked Dr. Baker many of the same questions he’d asked Dr. Lindsey Thomas before lunch. He started with, “How do you define ‘complicating’?” Dr. Baker answered, “I use the word ‘complicating’ the way I think most physicians use the word ‘complications’ . . . Somebody goes in for hip surgery and they develop a blood clot in their leg. That’s a complication.” Mr. Nelson asked him about the “Other Contributing Conditions” part of the death certificate, and Dr. Baker said that those conditions are relevant. “We don’t put something on there that doesn’t play a role.” Illicit drugs, heart disease, and hypertension all played a role in Floyd’s death.
Mr. Nelson got Dr. Baker to point out many of the same medical points as Dr. Thomas had earlier in the day: That at 540 grams, Floyd’s heart was enlarged; that two of Floyd’s arteries were 75 percent blocked; that Floyd’s right coronary artery was 90 percent blocked; and that 75 percent blockage (or more) can cause sudden death. Dr. Baker also stated that Fentanyl is a respiratory depressant that slows breathing, lowering oxygen levels, and methamphetamine is a stimulant that makes the heart work harder. He said meth is not something he would want to see in the blood of a man with heart disease. Dr. Baker certifies deaths by overdose hundreds of times per year, and he said he has certified deaths by Fentanyl overdose for people with Fentanyl levels that were equal to Floyd’s, lower, and higher. Dr. Baker said he has seen levels as low as 3 ng/mL that caused overdose deaths; Floyd’s level was 11 ng/mL.
Mr. Nelson asked the medical examiner for his opinion on the prone position, and Dr. Baker said that according to medical literature, it is not inherently dangerous. This contradicted testimony from earlier in the trial, when some witnesses claimed the prone position is dangerous and causes positional asphyxia.
Referring to transcripts of interviews that various agencies had conducted with Dr. Baker, Mr. Nelson’s questioning revealed the following timeline:
- May 25th — George Floyd dies.
- May 26th — Dr. Baker conducts his autopsy on Floyd, without viewing video of his arrest. Later that day, he has a meeting with Hennepin county attorneys, and he tells them that the autopsy found no physical evidence that Floyd died of asphyxiation.
- June 1st — Dr. Baker had viewed the videos by now. The toxicology report is issued, and the autopsy report is completed and filed.
- July 8th — Dr. Baker is asked “but for” questions on conference calls with many people from the DOJ and FBI.
Mr. Nelson asked the doctor about his past comment that had Floyd been found at home with the same Fentanyl levels, he would have called Floyd’s death an overdose. Dr. Baker explained:
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.
He added that it was Floyd’s interaction with police that “tipped him over the edge” in combination with Floyd’s other health problems.
Mr. Nelson wrapped up his cross-examination with some questions about the mechanics of Floyd’s death. He asked if Mr. Chauvin had blocked Floyd’s carotid artery. Dr. Baker said he had not, and even if he had, the other artery could have supplied blood to Floyd’s brain. The doctor acknowledged that Mr. Chauvin’s knee had been on the back of Floyd’s neck, and he said that doctors don’t often see pressure to the back of the neck causing asphyxiation.
Mr. Nelson’s final question of the day was: “In terms of the placement of Mr. Chauvin’s knee . . . would that, anatomically, cut off Mr. Floyd’s airway?”
Dr. Baker answered: “In my opinion, it would not.”
During Mr. Blackwell’s redirect, Dr. Baker said if he had to do it again, he wouldn’t change his topline cause of death. The other conditions were contributing causes, but not direct causes. He would still classify the death as a homicide and would not change the death certificate.
Photo: Credit Image: © Pool Video Via Court Tv via ZUMA Wire.