Carbon monoxide in his blood stream and other conditions. The family of Daunte Wright where waiting to see if charges will be filed against kim potter. Potter and the citys police chief resigned yesterday. Joining us now, nbc Morgan Chesky in Brooklyn Center, minnesota and law professor many Melissa Murray and paul butler. Welcome all. Shaq, first to you, take us through whats been happening this very detailed discussion today on heart functions and george floyd throughout the morning and i understand, first you have a report from the journalist thats been allowed in the courtroom to represent all of us. Reporter it seems as if the jury is engaged and taking notes. This Pool Reporter notes when you heard the opinion from dr. Fowler, the key opinion saying it was a sudden cardiac event during his restraint by police and mentioned contributing factors, thats when you heard or saw all the jurors start taking notes. They have been doing that throughout the testimony. Thats something they have been doing consistently as you heard from other medical experts and andrea, were in the phase of the trial now. We knew this was coming but where you have several different experts, intelligent people, world renowned people and highly respected people in many instances come up and give varying opinions and that is the purpose here. The defense, their job is to create doubt and poke holes in the testimony that you heard for the past two weeks from the prosecutions experts and thats what youre starting to hear. Dr. Fowler contradicting testimony youve heard hearing its a sudden cardiac event you had a cardiologist say no, George Floyds death was gradual. Youre hearing other elements and contributing factors come up for the first time. We heard and went through to check on this and for pretty much the first time, you heard the possibility of Carbon Dioxide poisoning being a potential cause of death or contributing factor to george floyd, not the knee on his neck for that 9 minutes and 29 seconds. That is the purpose of dr. Fowlers testimony and youll continue to hear and dr. Fowler is controversial and facing a federal lawsuit from the family of anton black when he was the chief medical examiner, it was a similar case mr. Black who was a teenager had a struggle with police and tased and put in a prone position for about 6 minutes i believe it was and during that interaction, he died and mr. Fowler, dr. Fowler ruled his death to be an accident rather than asphyxia, which other medical professionals said it clearly was. Thats what were facing and seeing in the courtroom. This is again, part of the defense doing what they can to introduce as much doubt as they can in this case against derek chauvin. Joyce vance, will the prosecution on redirect be able to bring up that anton black case in baltimore or will that be ruled out by the judge . Can you bring it up because he is an Expert Witness or not . So, the prosecution when they crossexamine this expert, they can test his credentials. They can look into whether or not he has bias. This is a civil lawsuit brought by the family that hasnt been decided yet. So the judge wont permit speculation about that particular lawsuit. But we cant really evaluate how successful a witness is until we see how they stand up on crossexamination, and so the thrust of the prosecution here will be to try to elicit testimony from this expert that shows he has in the past had a propolice bias, the judge will try and the defense but the judge will protect the record because this is all a matter of whether a verdict if the prosecution gets one can with stand scrutiny on appeal. So the judge will keep the prosecution from going too far into that dangerous territory of potentially prejudice information to keep and protect the integrity of any verdict they get. And we do have breaking news as we had suggested at the top. There is news out of that case on dante wright. Morgan chesky is there. What are we learning whether there have been charges against kim potter, the Police Officer . Reporter andrea, youre absolutely right. Within the last few minutes we heard from the county attorney here in this area and it is official, Second Degree manslaughter charges coming against former officer kim potter. That 26year veteran of the force right here in Brooklyn Center who submitted her resignation yesterday following the sunday shooting death of 20yearold donte wrielgt. The video was released on monday and captured the moment as potter reached for her side arm saying taser, taser, taser before firing the single shot that a medical examiner says was the shot that killed daunte when it struck him in the chest and he died a short time later. This is a charge we anticipated coming at some point today. Its important to note you could be charged with Second Degree manslaughter if you knowingly or consciously take a risk that results in the death of a person. We do know that at this point in time there is no official response from the family of Daunte Wright. We anticipate to hear from them at some point today in response to this. In addition to the charges coming against kim potter, we know the police chief here in Brooklyn Center also resigned yesterday, andrea and this entire department has now been placed under the responsibility of the mayor. The city manager who used to look over this has since been relieved of his duties. So a lot happening today. Well keep a close eye on this as it continues to go on and keep in mind, this shooting is still under investigation by the minnesota burro of criminal apprehension at this point in time. Andrea . Thanks so much, Morgan Chesky. Of course, there are disruptions as you know so well every night since. Let me ask Melissa Murray as a lawyer and law professor. Tell me the difference now between Second Degree manslaughter. Are there any charges that you think might have been higher charges, homicide charges against this officer . Well, manslaughter is a species upon a range of homicide crimes that might have been charged here but all of them turn on the actors state of mind at the time the conduct took place. Again, the investigation or initial investigation suggested that officer potter mistook her gun for a taser when she shot Daunte Wright so again, that seems to speak to the question of negligence or even recklessness but not necessarily intent. So typically, some of these murder charges, the most serious murder charges will flow from intent, premeditation, thats not on the table here. The real question is whether or not a seconddegree murder charge, which could be about recklessness maybe on extreme form of negligence in minnesota or manslaughter would have been on the table and it seems here that manslaughter was where they settled. And of course, we dont know all the evidence but we certainly have heard the audio tape where she says quite in shock, holy blank, you know, i shot him. So she seems shocked by what she had done, as well as everybody else, of course who has seen that horrible tape. Sorry, paul butler, i wanted you to weigh in on this, too. So we now have two Police Officers or former Police Officers in minnesota charged with Second Degree manslaughter for killing an unarmed African American man. Officer chauvin also faces those charges along with a much more serious murder charge that he faces. I think that there still needs to be an extensive investigation of the officer who killed mr. Wright. Taser mistakes happen but theyre very rare. Officers are trained to keep their tasers and guns in different locations. Tasers are designed to look really different from guns. Often, they have bright colors and different grips so how did the officer make this mistake with fatal consequences . There was another case in San Francisco oscar grant also was killed by an officer who claimed he made the same mistake. That officer was convicted of involuntarily manslaughter. You know, you make that point because weve seen the pictures how different. Theyre not always different colors but often, theyre a bright yellow or orange if theyre a taser and different weight, different grip as you point out but paul, at the same time, another piece of this is that she had come from training that very day apparently she had been involved in training. She was supposed to be an experienced trainer of other police so it gets to the larger issue of how police are trained. How police are trained and also, why this officer would taze a person doing a traffic stop for expired tags. He was unarmed and not suspected of any dangerous crime. With these cases, there is always the need for accountability for the individual officer but for the safety of the citizens of the state of minnesota, of course, questions about training, about competency, about how officers like the two who are now charged with involuntarily manslaughter, how they are allowed to remain on forces in minnesota and how many other officers like them are still out there . Joyce vance, i wanted to get to that because this also reminds me of that awful instance that we saw the viral video that just came out of a december traffic stop basically in virginia. The officers in these two instances going to tasers or other drawing guns at all when it is a traffic stop and they can follow the person. In this case, they knew where he was going. They knew his identity. They could have followed him to his home. Thats a conver vags what we want police to do. That started under the name of defending the police and that particular choice of words drew a lot of concern. Here were beginning to consider maybe they arent the best people to confront citizens with minor traffic infractions. Joyce and team, were going back to the trial and youve got eric nelson questioning dr. David fowler. What is that . Cardiac arrhythmia due to hyper tense sieve cardiovascular disease during restraint. Now, in terms of the other contributing factors to mr. Floyds death, did you, as a part of your review make other considerations to things that may have contributed . Yes, i did. Id like to discuss with you Carbon Monoxide or co. Okay . Youve reviewed all of the videos in the case, correct . I did. Did you Pay Attention to where mr. Floyds head was positioned relevant to the squad car . Yes, i did. Which way was his mouth facing . He was facing towards the rear of the vehicle and the tail pipe or tail pipes. And let me just ask you floyd died from carbon. In Carbon Monoxide poisoning, no. Id like to, if the court can and before the court does, the next slide has a screen shot from officer kings Body Worn Camera at 20 24 09. Do you see that there . Yes. How about now . Yes. Your honor, i have independently marked this single slide as exhibit 1058. Based upon discussions with counsel, id move for its admission. Objection. 1058 is received. Permission to publish . All right. Dr. Fowler, based on your review of the videos and evidence, were you able to determine if the vehicle was running . There was evidence that the vehicle was running. What would that evidence consist of . What i observed was a collection of fluid, if this is working, collection of cloud objection your honor, may we approach . Right now there is a side bar. Eric nelson had asked dr. Fowler how he knew the car was running. Earlier the issue was raised whether part of his medical problem contributing to death could have been Carbon Monoxide poisoning from the car running where he was asleep for awhile and then of course, was in the car for awhile. And theyre about to come back from the side bar. It will be dr. David fowler on the stand, eric nelson the defense questioning him. Excuse me, theyre still at the side bar discussing i guess what he can say. There was a prosecution objection to that line of questioning about the car running, how he knew the car was running and what he did get out and this could always be struck from the record is there was a collection of fluid and at that point, the prosecution interrupted. Shaq, youre outside the courtroom. The courthouse. Were talking now about the car running. The car had been running for awhile because he had been in the car and according to the woman who was next to him, her testimony, he had fallen asleep, which of course, i guess, was part of their whole case that he had been on some drugs. Shaq . Reporter right, andrea. This is a new element we heard from the defense as they were questioning dr. Fowler here. One note on the side bar, one thing the judge made clear of is he does not want attorneys to argue their objections in front of the jury. Instead, they usually will launch the objection and say the grounds for it and if there is need for further discussion, they will list the arguments in the side bar conversation and it looks like theyre coming back to the testimony now. Yeah, the trial is resuming. Lets go back and listen to eric nelson, the defense lawyer questioning dr. David fowler who is an Expert Witness, medical examiner. Dr. Fowler, based on your general knowledge as a forensic pathologist, your personal experiences, what comes out of a cars exhaust . Typically we see the products of combustion. It an internal Combustion Engine coming out the exhaust and the Major Products of combustion are going to be water vapor, Carbon Dioxide, Carbon Monoxide and a couple of other very small other particlit and minor gases that come out of the exhaust pipe. Is Carbon Monoxide toxic . It is an extremely toxic gas. How does it act as a poison . Carbon monoxide attaches to the hema globin in our red blood cells and attaches more tightly than oxygen so it competes for the same binding position on the hemo globin than ox gin does and because it binds more firmly, the oxygen cant displace it. As the percentage of Carbon Monoxide bound to your hemo globin goes up, you lose that portion of your oxygen carrying capacity. So if you have a 10 Carbon Monoxide saturation in your blood stream, youve lost 10 of your oxygen carrying capacity. Okay. Can that cause ultimately, death . When you get to levels way in excess of 50, 60 , people typically, even Young Healthy individuals will start to die. The issue is that people with significant Heart Disease and reduced capacity in their heart are going to be adversely affected earlier. So there are certainly many examples in the literature of people dying in an environment where multiple people are exposed but one person dies and that seems less than 20 and the others die at varying levels above that. So its not universal that everybody will be require to get to 60, 70, 80 as a Young Healthy individual. People with predispoing positions that are vulnerable will die at lower levels. In terms of the literature, are you familiar generally of the literature on Carbon Monoxide poisoning . Yes. Specifically are you familiar with the paper by de mayo and dana on Carbon Monoxide poisoning in open spaces . Yes, that is a paper that came out in the late 18s, i believe. Is this here as part of your power point that article or title . This is the title sheet or title portion of that particular paper that was published by the two doctors. That was in the late 80s you said . Yes. Are you aware of cdc warnings of carbon doxide in open spaces . Yes. Can you explain what this slide represents . This is the outdoor air recommendation, were talking about indoor air. Outdoor recommendations by the epa and recommending individuals are not exposed to nine parts for million for eight hours and it can put you at risk for symptoms if not more and if you go up, not much of an increase, that exposure limits drops to one hour. So in terms of the cdc versus the epa, what does the cdc say . About the same. Just be careful of Carbon Monoxide regardless of your environment. Are you familiar with the Consumer ProductSafety Commission scale . Excuse me, the Consumer ProductSafety Commission . Yes. Is that the information that you obtained for this case . So this is the top of the page that they refer to and if you go to the next slide, it actually says what it says on the page, and basically, theyre saying that most people will not experience any symptoms from a prolonged exposure to Carbon Monoxide between 1 and 70 parts per million. Some Heart Patients may experience an increase in chest pain, in other words, become symptomatic in that range. As co levels increase and remain above 70 parts per million, symptoms can include headache, fatigue and nausea and once you get above 150 to 200 parts per million, people become disoriented, unconscious and death are possible. So the higher the level, the more rapid and serious the potential consequences of exposure to a source of Carbon Monoxide is. Are you also familiar with the World Health Organization standards . Yes. Is that the next slide . This is just again the header from their document, relevant information is on the next slide. And they go a little further than the epa giving us more data and what they do is theyve got the same nine parts per million for eight hours. Their recommendation is not more than 26 parts per million for eight hours, not the 35 that the cdc the epa has. At 52 parts per million, the risk of exposure issues occurs in 30 minutes at 52 parts per million and at 8 7 parting per million, 57 minutes getssorbed t of Carbon Monoxide. Youre not a mechanic, right . Right. Are you aware of general standards in terms of the emission of Carbon Monoxide by vehicles . Yes, i am. Its part of the general knowledge of forensic pathologist have to the different types of sources of Carbon Monoxide. Would that include the California AirResources Board . Yes, this is one of the most strict automobile emission regulations. Okay. What is the regulations stand for . So in california it been adopted in about 14, 15 states around the country. So california has been copied by various other states. Some states have not copied it. I could not find any reference to minnesota being a carb state but adopting the california stringent regulations, a vehicle may emit up to 1,200 parts per million of Carbon Monoxide from its exhaust. Im going back to the prior slide. Where would that fall within the World Health Organization . World Health Organization guidelines . They go to 87. Were talking 1200. Were talking 12, 13 times. Again, youre not suggesting to the jury mr. Floyd died of Carbon Monoxide poisoning . Not exclusively, no. How would you be able to determine that the role that Carbon Monoxide played in a particular death . Typically and the easiest way for a medical examiner to do that is to have the blood tested by a laboratory for what we call the saturation and will come back from the laboratory giving us a percentage saturation. To your knowledge, was mr. Floyds blood tested for Carbon Monoxide . I could not find a reference to it, no. Now, the previous articles that we kind of looked at, the demaio from the late 80s are there more references of the Carbon Monoxide spaces . Yes. May have gotten mixed in here. I dont think i put this into the power point. Okay. Mr. Nelson. This is a recent study or case report that came out of poland where a taxi driver committed suicide by taking his vehicle, parking it in an open space, taking one of the mats out of the vehicle, putting it behind the vehicle and laid down on the mat and inhaled the exhaust and he ended up with a very high level of Carbon Monoxide in the 80s. Certainly sufficient to being exclusive cause of death in that particular case. It provided no new information carbon doxide is dangerous and comes out of exhaust. It replicated what demaio and dana had done 30 years before. But what was done in that particular case was that the authorities tested the amount of Carbon Monoxide coming out of the exhaust. So they did a recreation, reenactment and took Carbon Monoxide sensors and put them at a place where the mans nose and mouth were and the Carbon Monoxide coming out of the vehicle was monitored. So the principle that you can test a vehicle and make a determination exactly how dangerous it is was probably tested in that particular case and they found that when the breeze was blowing or the wind was blowing, at or about this mans face and he was about a foot away to give you a reference. The wind was blowing, the amount of Carbon Monoxide picked up by the sensor was 200 parts per million. And when the wind dropped, it went up to 790 parts per mill. Which is again, almost ten times the World Health Organizations recommendation. So in the area close to an exhaust, youre going to have a much higher level of Carbon Monoxide than you would if youre three, four feet away. Okay. Now to your knowledge, were similar experiments done in this case or recreations . I did not see any information that indicated that a similar recreation was done in this particular case, no. In terms of modern vehicles, they have cad lit tick converters, correct. Absolutely. What does a cad lit tick converter do relevant to Carbon Monoxide . It reduces it dramatically. In the era before the amount of Carbon Monoxide coming out of a typical exhaust would exceed 30,000 parts per million and could be as high as 70,000. The modern emission control that you see on these from the california requirements, which are again the most strict have reduced it by 30 times to somewhere close to 1,000 to 1200. In terms of can you describe for the jury what a pulse oxometer is a device you put on the finger, a little clamp and it reads two things. Your pulse rate and the oxygen saturation in your blood. So it counts the pulses and it reads how much oxygen youre carrying in your blood by looking at the color of your fingernail. How does Carbon Monoxide come into play in terms of pulse oximeter . It appears to be oxygen. It changes the blood to a color which the pulse oximeter thinks is oxygen. So if you take somebody who has 50 saturation of Carbon Monoxide, it will still read that the person is 95 oxygen. It doesnt tell you that there is 50 . If it was put on mr. Floyds finger and again in the hospital, the pulse oximeter does not give us any information allowing us to say he was or was not under the inflence of some degree of Carbon Monoxide intoxication. How long does Carbon Monoxide stay in the blood stream . So it stays in the blood stream if you want to treat a person and put them on 100 oxygen, the heart life is about an hour and a half to two hours. If youre exposed to ambient air, it takes much longer to get rid of the Carbon Monoxide. So essentially removing that Carbon Monoxide from the blood stream is a reversible process. It not ir reversible, it is reversible so it will at some point associate so we generate a small degree. Very low sub 1 and binds to the home globen and will be blown at some point. How much Carbon Monoxide needs to be in bloodstream to diminish the oxygen supply . For a young, healthy individual you want to probably exceed the 6 0, 70, 80 range. Thats what we typically see. In individuals with risk factors, that can be far, far less. What type of risk fact tors would you look for . So these are particularly, the individuals that are particularly at risk are people with cardiovascular disease as we saw in mr. Floyd and people with chronic obstructive lung disease and kidney disease, et cetera. The real high risk one is going to be heart. And what percentage would you expect when someone presents with those conditions . Very difficult to predict because everyone is different. There are studies out there where as little as 6 saturation with Carbon Monoxide in an individual who is exercising with Heart Disease will start causing arrhythmia. It a very low percentage. You have to have the Heart Disease and exercise but at about 6 , there are studies done in a controlled Laboratory Environment where people started showing ekg changes and premature contractions so it been present lower individuals than a young, healthy individual. Now in terms of findings of the autopsy, are there things that can determine what the presence of Carbon Monoxide observations that the pathologist can make . It typically that looks like it cherry red in color. Its not pink or slightly dark red color we would see for the oxygen blood. Its a very bright cherry red. The reason the pulse oximeter gets confused, as well. When you get levels of 50, 60 rchs70 it stands out. When you look at levels like 10 , it doesnt and is not easy to see. A typical smoker, one pack a day can have a hemoglobin of 6 . Two packs a day can get up to 12 . We dont see that as forensic pathologist because there is so much background color from the blood it lost in that. I would expect a pathologist when there is a substantial amount to spot it relatively easily but i would not expect somebody to see the lower levels that can still be a factor. And to do that, you would need to test the blood . That would be the energies. So if youre not saying Carbon Monoxide caused his death, can you eliminate it as a contributing factor . The only way to eliminate Carbon Monoxide as a contributing factor, would be to ensure there was none in his blood or a very, very low level in his blood. So in mr. Floyd, it robs him of an additional percentage of oxygen carrying capacity. Whether that be 5 , 10 , 15 , it takes away from the important factor of getting blood to his heart muscle. So this is just another potential insult, another brick in the wall unfortunately for the circumstances here. Now, ultimately, the officers werent affected by this . No, they were not. And why would that be . Well, another two to three feet away and potentially hopefully much younger and hopefully dont have Heart Disease. So with every foot or more away, the amount of Carbon Monoxide in their particular bubble is going to decrease. Now, so weve discussed the heart. Weve discussed Carbon Monoxide. Did you eliminate certain causes of death, as well . Yes. Specifically referring to asphyxia . Correct. How would you describe the investigation of ka custodial deaths compared to other deaths. Needs to be done very carefully. Are there other variables to consider . Absolutely. Huge number of variables as we obviously can see in the case of mr. Floyd, as well. In terms of this article here in your power point presentation, whats the significance of this . This is an article put out in 1992 by dr. James luke and dr. Donald ray. Dr. Donald ray was one of the first pathologist to theoryize putting somebody in a face down position was dangerous. And that was based on observations of cases people were placed in a prone position and died. So his conclusion was that may well be a factor and needed to be considered but what dr. Ray does say and later on recanted that to a large extent but what he does say is that these are very difficult complex cases, dont rush to judgement. Make sure youve considered all of the potential issues that are at play in these particular cases and only you can talk about a crystal ball in this particular case and the risk of underestimating the importance of common sense and the fact that there are no easy answers in such deaths. In your experience as a forensic pathologist, have you had the opportunity to perform a Death Investigation and autopsies of in custody deaths . Yes. So in this particular case, weve heard a lot about hypoxia, which organ is more sensitive to hypoxia . The brain is most rapid licensetive to hypoxia. In your review to the materials, did you have an on opportunity to review testimony of dr. Baker in prior proceedings . Yes. Dr. Baker in his testimony referenced some studies in terms of the effects of positional asphyxia. Are you familiar with those studies . Yes. Did you take those studies into consideration as far as your analysis this of this case . Yes, this is the current state of science or the Knowledge Base with regard to this very difficult situation. So lets talk just simply about the prone position. Do people sometimes sleep in the prone position . Yes. Approximately 7 of the Adult Population sleep face down. In terms of medical examinations, treatments, are people kept in the prone position . In certain situations people are examined in the prone position there are therapeutic maneuvers where people are deliberately placed in the prone position. One of the best examples right now is covid where patients will be put in a prone position, which is face down and it improves their ability for oxygen exchange. Not decreases it. So the prone position by itself does not have or at least there is no evidence right now that that is a significant issue. In terms of this particular case of course, the prone position is not in a hospital setting, right . It in a street, agreed . Correct. And i just generally speaking, if i were if a person were to lay down on the street in the prone position with nothing on top of them, is that in and of itself inherently dangerous . No, the scientific studies basically have looked at the issue of the prone position with and without weight and made a determination there is really no significant impairment of the individuals respiratory function and those studies were carefully crafted let me interrupt you for a second, doctor. Whats the kind of the leading study on weight applied to someone in the prone position. There are several but the one recently read was by dr. Mark crawl and a couple other coauthors. Is that this paper here . Yes, i believe that is the one, yes. Positional compression and restraint asphyxia, a brief review . Yes. In terms of this study, can you just explain this study . Can you explain the setting of the study, et cetera . This is a review paper he considers his own work where no evidence of any kind of compressional asphyxia was found in individuals in the socalled hog tie situation, which is prone with their hands handcuffed behind their backs. Additional restraints around the ankles and two tied together. That is the classical hog tie position. And then weights were applied to the individual up to 102 kilograms, which is 225 pounds and found again, no significant disturbance to their ability to exchange and breathe. So the final conclusion was and there are about 23 different studies out there. Dr. Baker referred to in his previous testimony previously environment. And in this paper, dr. Crawl says positional asphyxia as the term is used in court today is an interesting hypothesis unsupported by any experimental data. So let me ask you pursuant to the courts order, you were permitted to review the testimony or watch the testimony of other Expert Witnesses in this case, correct . Yes. Did you do so . Some of them, not all of them. Okay. Did you hear criticism of this paper . Yes, i did. And do you think that the study was flawed based on its methodology . So, the study was asking one specific question. Is the prone position dangerous . When you craft a experimental process to look at a particular process, in this particular case was the prone. You want to eliminate all other variables. You want to eliminate fear. You want to eliminate exertion. You want to eliminate environmental conditions, other than and focus entirely on that one entity. So agree that what is happening in this particular situation, they didnt use people who had Heart Disease. They used young, healthy volunteers. The surface they were lying on is not asphalt. The individuals are not in fear of their life. They knew they could be pulled out of that at any time and there was no fear and adrenaline and all of the other issues, al they simply were doing is evaluating just the prone position and the weight on the back from the prone position and found it had no effect. Now you can go back and look at the other issues if you want to at some stage. In terms of this study by putting weight on the back, how did that work . So they were using bags of weight, sacks and they continued to place them over the thorax evenly distributed across the chest and upper abdominal area, the area which is where your lungs and socalled bellows and so it puts pressure on the diaphragm, if because of the abdominal weight and on the test and it looks to see whether or not individuals can still move air in and out and they did not find any significant impact. Have you ever seen an image of like a team, a Baseball Team winning the world series . You mean a human pyramid . Right. Yes. Is that kind of the analysis or analogy that they bring . Yes. Kind of lots of people piled on top and someone has to be at the bottom, right . Correct. There are other in terms of the studies you talked about this particular paper, that was a review of other studies, right . And other work, yes. And there were 23, i believe, you said. That was the testimony d baker stated in the previous legal proceeding. Some of the other studies that they reviewed . Yes, these are just a short list, its not all of them. Just illustrating the developing information and really this gathered a lot of steam over the last couple years, so prior to many studies, the wisdom of the position is dangerous were still accepted but you can see from 2007, 2012, 2013, 2014 people are really beginning to really adding to the body of knowledge in the medical sciences and beginning to challenge these theories. In terms of, again, just the research, the criticism offered by previous experts was that it wasnt real world where some of these studies looking at real world situations . Correct. Which of those studies . So, the real world ones are two papers by dr. Hall, i think, probably are the ones that stand out. The first paper was she took a city at one point of 1 million. Worth 1. 1 million, it was a city of 1. 1 million residents and in that there were 1,296 cases where there was a forceful restraint, and the only death that they found in that particular case was a person who was not in the prone position, and they evaluated prone versus nonprone and statistically found no difference. And so relatively small study. So they did a bigger study where they took four cities and looked at almost 5,000 consecutive force events and concluded and the final conclusion was, concluded their data support the Human Laboratory data, which are these ones in the controlled environment that the prone position has no clinically significant fit on subject physiology. Now did dr. Krol publish a paper relevant to the weight of a Police Officer . Yes. Is that this study here. Yes. Can you just describe for the jury this study by dr. Krol and others and the officers weight being a factor in the analysis of prone position and asphyxia . His conclusion is it doesnt matter how much the officer weighs. 140, 150, 200 pounds. It doesnt make a huge difference to the outcome. What he did say is that with a double knee restraint, specifically, two knees on the person, it has a modest influence on the weight applied to these are not testing respiration. These were weight tests on dummies. So what hes measuring here is if a person weighs 140 pounds and they kneel on somebody, how much weight are they transferring. With a single knee, it didnt matter what weight the individual was. With a double knee, up to 23 of the body weight could be transferred to the dummy. Up to, im sorry, how much . 23 . They were not looking, when you see it, it has a modest influence. It has a modest influence on the weight transferred, not respiratory activity. Okay. Do you know based on your review of the materials, were you able to ascertain officer chauvins weight . I was informed, yes. I have seen that weight. And what is that . 140 pounds is what i was told. Now, you also in reviewing the videos, you see he has two feet on the ground with the exception of one small moment. Yes, that was what i did actually see in the video. So what portion of mr. Chauvins weight was transferred onto mr. Floyds body . Hes using a singleknee technique through the greater majority. His other knee is either on the bicep area or on close to the left chest wall. So singleknee tech, less than 23 , but even if he applied both knees, which he would have transferred 23 of his body weight, for a 140pound person, that would be between 30 and 35 pounds. Less than 225 pounds from the laboratory. Yes. So in terms of, you know, let me ask you this first. In terms of the placement of officer chauvins excuse me knee to mr. Floyd, was it your opinion that mr. Chauvins knee in any way impacted the structures of mr. Floyds neck . No, it did not. None of the vital structures were in the area where the knee appeared to be from the videos. Now, again, in terms of your Death Investigations, you have reviewed photographs, you have reviewed the autopsy photographs, things of that nature, correct . Yes. Were any signs of generally speaking, do signs of injury play into your analysis as to the cause of death . Yes. How so . Well, you make an observation of such in this particular case, of a knee providing force to a particular part of the body, and then you go and you look at the same part of the body to see whether or not you can find corroborating evidence within the body itself. Either an abrasion to the skin, subcutaneous hemorrhage, hemorrhage into the muscles or other injuries that may be caused by the knee. And what injuries did you observe in the photographs of mr. Floyd . All of his injuries were in areas where the knee was not. In other words, they were on the front of his body. His face, his places where he was restrained, but there was absolutely no evidence of any injury on the skin to the subcutaneous tissue or the deeper structures of the back or the neck. Were there any broken bones, spinal injuries, anything of that nature . There were no broken bones documented. I did not see a description of the spinal cord in the autopsy report, but given that there was really no external evidence of the area, the muscles around the spinal column, i would be very surprised if there was any spinal cord injury in this particular case. So you referenced the back of mr. Floyd. Did you see any bruising to the skin . I did not see bruising or abrasion to the skin. Did you see any bleeding into the subcutaneous tissues of the neck and back . Not on the autopsy photographs, nor was it documented in the autopsy. How about to the muscles . The same. And so in your opinion, the absence of such injury, how does that speak to the cause of death . It speaks to the amount of force that was applied to mr. Floyd was less than enough to bruise him. So in terms of the knee, can you im looking at your powerpoint here, can you help us understand how the knee relates to questions of injury and force . Well, two structures that would be of concern in this particular case. One would be the actual knee itself. And the other would be the tibia, which is the shinbone. This diagram shows the shinbone, and this is this object right here. And if you remove that particular red circle i just put in, you can see that the tibia has a relatively defined front edge right over here. And you can feel it on yourself, but it is a nice ridge all the way down, which is actually quite prominent. And hard. And its right underneath the skin. And so that allows an unforgiving surface such as the shinbone to be placed on soft tissues which are more vulnerable and cause some degree of injury to that area. So thats the shinbone. The knee is actually not that much different. The knee is near the patella and you have the ends of the femur, the thigh bone, and the ends of the tibia just below. All of which are bony prominences, and again, right underneath the skin. And they can direct the amount of force. If you put a substantial, 30, 40, 50 pounds worth of force focused with your knee onto somebody, in my opinion is the chances of a subcutaneous or intermuscular hemorrhage is very, very high. And you didnt see that in this autopsy . It was not documented and its not visible on the autopsy photographs. In your career as a forensic pathology, have you looked at other strangulation type cases . I have yes, strangulation and other restraint situations where knees have been used, yes. Do you typically see marks in those cases . In manual strangulation, often you will see hemorrhaging into the muscles of the neck. And in cases where the knee has been used on the back, we often see a bruise consistent and at times we have matched it to video cam footage of where we see a knee being placed, yes. Including just fingerprints, finger marks, i suppose. Yeah, so just the pressure from somebodys fingers is enough to cause muscle hemorrhage in a manual strangulation case. Were not talking about a person putting weight on somebody. Just talking about somebody squeezing a neck. When you look at this case and you see the knee is involved, the shinbone is involved, would you expect to see a greater likelihood of bruising from just the fingers . Objection, your honor. Calls for speculation. Overruled. Sorry, can you repeat the question . Sure. In this particular case, where the knee is involved, there is allegations of it being used to force or subdue mr. Floyd, would you expect the knee and shinbone to have a greater likelihood to produce bruising . Than fingers . Yes. And is there any objective medical findings in the autopsy showing pressure placed to the back . No. Now, again, we have talked about hypoxia, and we can take this down now, judge. We have talked about hypoxia. What are the effects of hypoxia that you would expect to see if that were present . So, there are some observable symptoms when a person becomes hypoxic. Is that what youre asking . Yes. Yes. What are those . So people typically start to get a little confused. Disoriented. They may have visual changes. People have described little spots of light, gray curtain coming down. So there are visual abnormalities people will describe and complain of. They often become incoherent. They have difficulty speaking. What is happening with hypoxia is your brain is getting progressively short of oxygen. And so youre getting decreased function of your brain. And some of those are going to mimic intoxication by other sources. Did mr. Floyd, based on