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Live Coverage of Derek Chauvin Trial; Forensic Pathologist is Questioned by Prosecution; Lindsey Thomas Explains Cause and Mechanism of George Floyd's Death. Aired 10:30-11a ET

Aired April 9, 2021 - 10:30   ET



JERRY BLACKWELL, PROSECUTING ATTORNEY: Do you sometimes interview people also as a part of it?

THOMAS: Yes. The investigators who go to the scene may talk to family members. We certainly will talk to medical providers to get someone's past medical history. We often will interview or talk with law enforcement officers if they were the people who responded. It could be paramedics, EMS, troopers, just depends on the case.

BLACKWELL: I want to ask you about a phrase you used, "terminal events"?


BLACKWELL: Could you explain to the jury what is a terminal event?

THOMAS: Sure. So when we're investigating a death as medical examiners, as I mentioned, we want to know as much as we can about this person leading up to their death because that often, how they lived, will provide us information about how they died.

When I'm talking about terminal events, I'm talking about what happened in the period of time around their deaths, leading -- shortly leading up to their death. So for example, he was out shoveling snow, he came in, clutched his chest and fell over. That would be an example of a terminal event.

Or we know someone was driving a car, and went off the road. That would be what the terminal events were.

BLACKWELL: Do you also rely on training and expertise on how injuries occur?

THOMAS: Yes. As a forensic pathologist, that's one of the things we look at is -- and learn about, is when we see this type of injury, we associate that with this type of event.

BLACKWELL: What does the medical examiner then do at the conclusion of a death investigation?

THOMAS: So the ultimate goal is to complete the information that's needed on the death certificate. Specifically, the cause and manner of death.

BLACKWELL: Is a report generated?


BLACKWELL: What's the nature of that report?

THOMAS: Well, one of the main reports that's generated would be considered the autopsy report, and that's the report of the physical examination. But ultimately, the death certificate is kind of the final report.

BLACKWELL: Now, you told us as a forensic pathologist, you don't treat living patients --

THOMAS: Right.

BLACKWELL: -- so if -- if we wanted to have a discussion for example about measuring lung volumes or air reserves in someone, that wouldn't be your bailiwick as a medical examiner?

THOMAS: That would not be me, no. By the time I see them, none of that applies, yes.

BLACKWELL: Right. So Dr. Thomas, are you currently employed?

THOMAS: I work -- I'm kind of semi-retired. I do consulting, and then I work part-time at medical examiners' officers in Reno, Nevada and Salt Lake City, Utah.

BLACKWELL: Reno and Salt Lake City, Dr. Thomas?

THOMAS: They're places -- I really like the way the office runs, and I like still to be involved as a medical examiner.

BLACKWELL: Pretty good places to hike.

THOMAS: And good places to hike, yes.

BLACKWELL: So what did you -- where did you do your work before you were semi-retired?

THOMAS: Right before I retired, I was at the Hennepin County Medical Examiner's Office as an assistant medical examiner. And do you want me to go before that?

BLACKWELL: Yes, if you could tell us your work experience as a medical examiner, forensic pathologist.

THOMAS: Sure. Initially, I started after my training at the Hennepin County Medical Examiner's Office, working as a deputy and assistant, then assistant medical examiner, and I was there for many years.

And then in 1997, I joined the Minnesota Regional Medical Examiner's Office that was based in Hastings. And then I was chief of that office for 13 years, and we were the medical examiner's office for eight counties in Minnesota, the largest of which were Dakota and Scott Counties. And we also served as an autopsy referral service and medical examiner's office for many other counties in Minnesota as well as Wisconsin, and even one in Michigan.

And then when our office outgrew that space, Dakota and Scott Counties merged with Hennepin County and that's why then I came back to Hennepin County.

BLACKWELL: So over how many years have you performed work or services as a forensic pathologist?

THOMAS: Let's see, 37 now, 36?

BLACKWELL: And in Minnesota, how many counties?

THOMAS: Oh, gosh, well, I've been the direct medical examiner for eight counties, I've worked in offices that have been consultant to dozens of other counties.


BLACKWELL: And have you also performed those services in parts of Wisconsin?


BLACKWELL: When did you stop working at the Hennepin County Medical Examiner's Office?

THOMAS: It was early 2017, I retired from Hennepin County.

BLACKWELL: And how many autopsies would you estimate you have performed over your career?

THOMAS: Probably about 5,000 that I myself did, and then hundreds, maybe a thousand more where I assisted someone else or I supervised or I participated in some way.

BLACKWELL: So in 5,000 or so cases, you determined the cause and manner of death?

THOMAS: Well actually, way more than that. Because as medical examiners, we don't just certify the cause and manner of death for the cases that we do autopsies on. There are numerous other cases that get reported by law to the medical examiner's office where we don't do a physical examination.

So for example, an elderly person falls in a nursing home and gets a hip fracture and then dies a couple months later, that death has to be reported to the medical examiner's office. We will investigate that death by looking at the medical records and doing all of what I talked about, getting family input and medical provider input, but we generally will not do a physical examination. But still, by law, we have to sign the death certificate.

BLACKWELL: So you're still determining, then, the cause and manner of death?

THOMAS: Right, we're just not using a physical examination as part of it.

BLACKWELL: And using their medical records primarily?


BLACKWELL: Dr. Thomas, are you licensed presently?

THOMAS: Yes, I'm licensed in Minnesota, Wisconsin, Tennessee, Nevada and Utah.

BLACKWELL: Do you also hold any board certifications?

THOMAS: Yes, I'm board certified by the American Board of Pathology in anatomic pathology, clinical pathology and forensic pathology.

BLACKWELL: Have you worked with any professional organizations over the years related to forensic pathology?

THOMAS: Yes, I've been a member of many different organizations: Minnesota Medical Association, American Medical Association, the College of American Pathologists, American Academy of Forensic Sciences, and then I've been on the board of the Minnesota Coroners and Medical Examiners Association, oh, probably 30-plus years. And then I'm a member of the National Association of Medical Examiners, and I was on that board and a member of their executive committee for a number of years.

BLACKWELL: And that goes by the acronym, NAME, N-A-M-E?


BLACKWELL: What does NAME do?

THOMAS: Well, they're the professional organization of medical legal death investigators, specifically forensic pathologists, medical examiners and as an organization, they provide support to medical examiners, they provide information, they provide guidelines, accreditation program, an inspection program, lots of ways of assisting medical examiner offices.

BLACKWELL: Dr. Thomas, have you done any teaching?


BLACKWELL: Tell us about that.

THOMAS: I have been a clinical instructor here at the University of Minnesota Department of Pathology, I've done lots of law enforcement training through the Bureau of Criminal Apprehension here in Minnesota, as well as, oh my gosh, teaching everything from, you know, middle school science students through high school and college, and all kinds of professional groups, whether it's other forensic pathologists, other law enforcement, you know, you name the organization that comes into contact with death investigation, and I've probably talked to some of them at some point.

BLACKWELL: Do you have any publications?

THOMAS: That hasn't been a main focus of my career, but I was -- I have several, and early on was involved in an autopsy protocol that was ultimately published by the United Nations that's still in use.

BLACKWELL: So let's switch topics, and talk about your experience testifying in courts. Have you testified before in a court?


THOMAS: Yes, probably over a hundred times.

BLACKWELL: And is that predominantly in your role as a medical examiner?

THOMAS: It's mostly in my role as a medical examiner, where I did the autopsy and then the prosecution would call me to testify as to my findings. I've also testified as an expert witness consultant in cases where I didn't do the autopsy but I was called by maybe in a civil case, either by the defense or the plaintiff, if they thought there was a wrongful death or some question about medical malpractice, something like that.

And then I've also been consulted and testified in cases at the request of the defense, again not where I did the autopsy but where I reviewed someone else's work and then I consulted with the defense or testified.

BLACKWELL: And have you testified in Minnesota courts?

THOMAS: Minnesota, Iowa, Wisconsin, North Dakota, South Dakota, Pennsylvania. I think those are the ones.

BLACKWELL: So Dr. Thomas, are you being paid for your time and services in this case?


BLACKWELL: Could you tell us about that? How does it come about that you're not being paid for your time and services in this case?

THOMAS: Well, I didn't ask to be paid.

BLACKWELL: And so did you reach out to the state or did the state reach out to you?

THOMAS: No, no, you reached out to me. And you know, it just -- 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 help explain what I think happened.

BLACKWELL: So what were you asked to do, then, in this case?

THOMAS: Well, I was asked to review a lot of the materials, and come to an independent conclusion about what I thought the cause and manner of death were, and the mechanism for that cause.

BLACKWELL: Could you give the jurors a general sense, an overview of the kinds of materials you reviewed?

THOMAS: May I look at my notes?

BLACKWELL: Yes, if you need to refresh your recollection.

THOMAS: So I looked at the Hennepin County Medical Examiner materials including the autopsy report and toxicology and photographs and microscopic slides, things like that. I looked at the Hennepin County Medical Center records, so Mr. Floyd's past medical history from there, as well as Health Partners medical records.

Then I looked at a lot of interviews, many, many videos including body-worn camera videos, bystander videos, surveillance videos, some photographs, still photographs, timeline and then some medical literature and textbooks.

BLACKWELL: So were you the medical examiner who investigated or did the autopsy around the death of George Floyd?

THOMAS: No, that was the -- Dr. Andrew Baker, the Hennepin County Medical Examiner.

BLACKWELL: Do you know Dr. Baker?

THOMAS: I do. He was a pathology resident when I was on staff at Hennepin County many years ago, and then when he did his fellowship, I was one of the staff people there. And then after our offices merged, I worked again with him at Hennepin County.

BLACKWELL: So would you have been then part of his training in his early formative years?


BLACKWELL: All right. Do you consider him a friend?

THOMAS: I do, yes.

BLACKWELL: Have you talked to him about this case?

THOMAS: No, not since right after it happened.

BLACKWELL: But you did review his report?


BLACKWELL: As well as Mr. Floyd's medical records?


BLACKWELL: Did you review the history of terminal events for May 25, 2020?


BLACKWELL: So what --

THOMAS: And what was kind of unique -- what was absolutely unique in this case was the volume of materials I had to review. I've never had a case like this that had such thorough documentation of the terminal events.

BLACKWELL: And by way of the thorough documentation, what makes it so thorough in your opinion?

THOMAS: Well, the use of videos is unique in this case. Certainly as medical examiners, we use videos but there's never been a case that I've been involved with that had videos over such a long timeframe and from so many different perspectives.

BLACKWELL: Are you aware then of Dr. Baker's conclusions then on the manner of death?



BLACKWELL: Your honor, I'd like to show exhibit 193 that's been stipulated to subject to Dr. Baker's foundation (ph).

So first, Dr. Thomas, what do we see here on exhibit 193?

THOMAS: This is a copy of the certificate of death of Mr. Floyd.

BLACKWELL: OK. And so, Brett (ph), if we could kind of highlight just through the word underline? Just to make it a little bigger to see?

OK. Based on your review of the -- of the evidence and death certificate, do you agree with Dr. Baker's determination on the cause of death?

THOMAS: Yes, I do.

BLACKWELL: And is that by the word "immediate" on here?

THOMAS: Yes, cardiopulmonary arrest, complicating law enforcement subdual, restraint and neck compression.

BLACKWELL: Have you, Dr. Thomas, formed an opinion about the mechanism of death?


BLACKWELL: Would you tell us what that is?

THOMAS: In this case, I believe the primary mechanism of death is asphyxia or low oxygen.

BLACKWELL: So we'll come back to the mechanism in just a minute. Can you explain to the jury what this cause of death means and why you agree with it?

THOMAS: Well, it's kind of in two parts. So there's the cardiopulmonary arrest, which doesn't provide a lot of additional clarifying information. Because, in a way, everyone dies of when your heart stops and your lungs stop, that's cardiopulmonary arrest.

But as a forensic pathologist, I would use cardiopulmonary arrest when I'm -- to differentiate it from a cardiac arrest. So this is not a sudden cardiac death, a sudden cardiac arrhythmia. This is a death where both the heart and lungs stopped working. And the point is that it's due to law enforcement subdual, restraint and compression. That is kind of what ultimately is the immediate cause of death, is the subdual, restraint and compression.

BLACKWELL: And just so it's clear for the jurors, does cardiopulmonary arrest mean heart attack?


BLACKWELL: Does it mean fatal arrhythmia as a primary cause of death?


BLACKWELL: It simply means that the heart stops and the lungs have stopped?

THOMAS: Correct.

BLACKWELL: It's another way of simply describing death itself?

THOMAS: Right.

BLACKWELL: Can you explain what's referred to, looking here at the terms, subdual, restraint and neck compression?

THOMAS: Those were activities by the law enforcement agency officers involved. Subdual is subduing someone. Trying to restrain them is, in Mr. Floyd's case, involved handcuffing him, his positioning on the ground, the prone position, the people kneeling on him. And the neck compression is the knee on the neck specifically. Additionally, there was some back and other things being compressed by the officers.

BLACKWELL: So if you put all this together, cardiopulmonary arrest, complicating law enforcement subdual, restraint, and neck compression, what does that mean?

THOMAS: Well, 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.

BLACKWELL: And does this then also represent your own conclusion?


BLACKWELL: A conclusion you have reached and an opinion you hold to a reasonable degree of medical certainty?


BLACKWELL: Would you tell us what you reviewed in order to reach this conclusion?

THOMAS: All of those things that I mentioned earlier. The -- again, what's sort of unique about this case is that often, I would just review the medical examiner case file and that would provide information about what the cause and manner of death is. But in this case, the autopsy itself didn't tell me the cause and manner of death and it really required getting all of this other additional information, specifically the video evidence of the terminal events, to conclude the cause of death and manner of death.


BLACKWELL: When you make reference to something called the mechanism of death, would you tell us what mechanism of death means?

THOMAS: So cause of death is what's the thing, the disease or the injury or the process that caused someone's death. But the mechanism is kind of what was going on in the body at that time.

So for example, the cause of death might be a gunshot wound, but the mechanism of death might be blood loss related to that gunshot wound. Or you know, an infection that complicated that gunshot wound down the road, something like that.

So it's more the what was actually happening at the body level that resulted in the cause of death.

BLACKWELL: So focusing in on the mechanism of death here, how is it that the officers' subdual, restraint and neck compression caused Mr. Floyd's death?

THOMAS: So as I mentioned, I think the primary mechanism was asphyxia or low oxygen. And it basically is 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.

BLACKWELL: What's required for normal breathing, Dr. Thomas?

THOMAS: What is required? Well, there are kind of three components. You have to be able to get air in, so you have to have what's called a patent airway, and that could be nose, mouth, you know, soft tissues of the neck, the trachea, the larynx -- larynx, trachea, bronchi, all of that has to be open.

At the level of the lungs itself, there has to be adequate air exchange between oxygen coming in, carbon dioxide going out. And then finally, the way the lungs work is it's kind of like a bellows that when you suck in air, your diaphragm drops and pulls air in. And then when you relax, the diaphragm collapses and pushes air out.

So all three of those things have to be functioning in order to get adequate oxygen in.

So for example, if someone is smothered or strangled or they inhale a piece of hot dog or they have pneumonia such that their lungs are completely filled, then their airway is obstructed so that there isn't adequate air coming in, oxygen coming in.

Or if someone is in an environment where there isn't enough oxygen, so for example in a closed garage in which an old car has been running, there may be way high carbon monoxide. And in that case, they're perfectly able to breathe in and out but there just isn't enough oxygen.

And then the third would be if there's some kind of restriction such that your chest can't expand, your diaphragm can't expand so the bellows function isn't working.

And if any one of those components isn't working, then the result will be this mechanism of inadequate oxygen.

BLACKWELL: Doctor, how does narrowing of the hypopharynx fit into this?

THOMAS: Well, the example I would give that people are probably most familiar with is sleep apnea or snoring. If you, yourself or have a partner who snores, you know that especially in certain positions, the -- what happens is the hypopharynx, which is sort of the soft tissues at the back of your throat, will kind of collapse because there's inadequate air coming either forcing it out or forcing it in, which is why a CPAP machine works because it forces air through that floppy area. And if that collapses, then it makes it difficult to get air in.

BLACKWELL: So, Dr. Thomas, what do you rely on to reach your conclusion that low oxygen was the mechanism of death?

THOMAS: In this case, it was primarily the evidence from the terminal events, the video evidence, that show Mr. Floyd in a position where he was unable to adequately breathe.

BLACKWELL: So how does the autopsy report itself assist you or not?

THOMAS: So the way the autopsy really helps is it's great for ruling things out. So in this case, the autopsy ruled out, for example, underlying lung disease. Mr. Floyd had had a history of COVID, but there was no evidence in his lungs at the time of his death that he had any lung disease that would impair his ability to breathe.


And it ruled out injuries to the neck that suggest that his -- the bones in his neck had been broken, for example. And it ruled out a stroke, he didn't have a stroke. So it wasn't like his blood pressure was so high that, you know, he ruptured a vessel in his brain. He didn't have an aneurism, he didn't have -- or -- which is a ruptured vessel. He didn't have an embolism, which is a blood clot. He didn't rupture his heart. He didn't have an old heart attack or a recent heart attack or what's called myocardial infarc. So the autopsy is really great for ruling things out.

BLACKWELL: Dr. Thomas, just to focus on one of those, you said the autopsy ruled out a recent myocardial infarction?


BLACKWELL: How does it do that?

THOMAS: Well, it -- when a forensic pathologist examines a heart, one of the things they look at is the coronary arteries, which are the vessels that supply blood and nutrients to the heart muscle. And then the pathologist will examine the muscle of the heart, and if someone has had a recent heart attack, there may be evidence in the heart muscle of that damage. Or if they've had a prior and older heart attack, there will be scarring in the heart muscle that shows that area of damage.

BLACKWELL: Thank you, Doctor. Is it normal, as a part of your death investigation, then, to seek out and to look at the video?

THOMAS: Yes, oh, yes.

BLACKWELL: In this case, is there any particular video footage that struck you as more significant than others from what you saw?

THOMAS: Oh, gosh, this case there were so many. The body-worn camera videos were very instructive because they started -- well, and the Cup Foods video, because they showed how Mr. Floyd was behaving long before law enforcement interaction.

Then the body-worn cameras show the early interactions before there was any of this subdual, restraint, and compression. And then they show the interactions during the subdual, restraint. The bystander videos are really instructive as well as the surveillance videos from the scene at showing kind of during the time of the restraint. So there were lots, I would say.

BLACKWELL: So in terms of the video footage then either ruling in a cause or ruling out a cause, how did it inform your assessments about the cause of death, having looked at the video?

THOMAS: Well, it helped me rule in a cause and also rule out causes, I would say.

BLACKWELL: So did it help you to determine whether this was what I might refer to as a lights-out kind of death, a sudden death?

THOMAS: Right. So what I observed from all of these videos is this was not a sudden death. Mr. Floyd did not -- it's not like the snow- shoveling, where I told you somebody comes in, collapses and, you know, clutches their chest and falls over. This was -- there was nothing sudden about his death.

So that's what I would have expected if it was a cardiac arrhythmia or abnormal beating of the heart. Typically those are someone really falls over pretty quickly, and this was not that. Likewise, it was not the type of death that has been reported in

fentanyl overdose, for example, where someone becomes very sleepy and then just sort of gradually, calmly, peacefully stops breathing. This was not that kind of a death.

So I felt comfortable ruling out those as causes of death.

And then on the flip side, you -- I could clearly see from watching the video what happens to Mr. Floyd during this subdual, restraint, and compression. And what happens to his breathing, is it gradually becomes more difficult and then stops.

BLACKWELL: Doctor, tell us what is the bellows function?


THOMAS: Well, it's what your diaphragm does along with the muscles in between your ribs.