Derek Chauvin Trail: Week Five

The trial’s Week Five continued with testimony of 16 prosecution witnesses after Week Four’s opening statements and testimony from 19 prosecution witnesses.[1]  This summary of Week Five is based upon watching some of the livestreaming of the trial and reports in the Star Tribune, Washington Post, New York Times and Wall Street Journal that will be listed in a subsequent post while another subsequent post will cover commentaries about Week Five.

Prosecution Witnesses

20. Dr. Bradford Wankhede Langenfeld (Hennepin County Medical Center (HCMC)). As an emergency room physician, Dr. Langenfeld examined Mr. Floyd upon his arrival at HCMC in an emergency condition of cardiac arrest with a heartbeat not sufficient to sustain life.  This was a “PEA” state of pulseless electrical activity caused by low oxygen, which soon evolved into asystole or flatlining when electrical shocks to the heart cannot bring the patient to life. After being advised that no lifesaving means had been performed on Mr. Floyd by officers or bystanders at the scene before Chauvin took his knee off the man, but that paramedics in the ambulance had spent about 30 minutes in the ambulance trying to resuscitate Floyd, the doctor’s immediate goal was to try to re-establish “spontaneous circulation.” To that end, the doctor examined several possible causes of cardiac arrest and concluded that hypcoxia, or lack of oxygen to the body tissues, was the most likely cause. Soon thereafter, Dr. Lagenfeld pronounced Mr. Floyd’s death due to lack of oxygen or asphyxia.(On cross examination, the doctor agreed that lack of oxygen in the body could be caused by the presence of opioids fentanyl and methamphetamines, which the subsequent autopsy found present in Floyd’s body.) “At the time it was not completely possible to rule that out,” he said, “but I felt it was less likely based on the information available to us.” The doctor also said patients with cardiac arrest have a 10 to 15 percent decrease in chances of survival for every minute CPR is not administered.

21. Medaria Arradondo (Minneapolis Police Department (MPD) Chief of Police). Arradondo, who joined the MPD in 1989 and has been its Chief for the last three years, after reviewing his background and training, testified that around 9:00 p.m.on the evening of May 25, 2020, he was advised of this incident by telephone at his home.  After immediately notifying Minneapolis Mayor Jacob Frey and the Minnesota Bureau of Criminal Investigation, the Chief went to his office downtown. There he first saw the video (without audio) of the city-operated surveillance camera, which made it difficult to determine what had happened.

Around midnight at his office, a community member called and asked if he had seen the “video of your officer choking and killing a man at 38th and Chicago.” This was the video taken by Darnella Frazier (then 17 years old, )which the chief had not yet seen.

Soon thereafter, however, the Chief obtained and watched that video and immediately concluded that “the facial expression of Mr. Floyd . . . does not appear in any way, shape or form [to reflect] light to moderate pressure” as required by MPD policy. Moreover, “once there was no longer any resistance, and clearly Mr. Floyd was no longer responsive and even was motionless, to continue to apply that level of force to a person proned out, handcuffed behind [his] . . back, that in no way shape or form is anything that is policy, part of our training and is certainly not part of our ethics or values.” Chauvin also failed in his duty to render first aid before the ambulance arrived and to deescalate the situation with no or minimal force if they can.

The Chief added that the MPD moto is “to serve with compassion,” which means  that every police officer needs “to understand and authentically accept that we see our neighbors as ourselves, we value one another, we see our community as necessary to our existence.”  To that end, each officer signs a document that he or she knows the contents of the MPD policy manual, which says in part that an officer may not detain a suspect “longer than necessary, and the copy signed by Chauvin was shown to the jury.

“Once Mr. Floyd had stopped resisting — and certainly once he was in distress and trying to verbalize that — that should have stopped,” the chief said after spelling out department policy on when to use force vs. calming a situation through de-escalation tactics.

“There’s an initial reasonableness of trying to just get him under control in the first few seconds,” the chief continued, “but once there was no longer any resistance, and clearly when Mr. Floyd was no longer responsive and even motionless, to continue to apply that level of force to a person proned out, handcuffed behind their back, that in no way shape or form is anything that is by policy. It’s not part of our training and is certainly not part of our ethics or values.”

The next day,  the Chief publicly announced his decision immediately to fire Chauvin and the other three officers.

Under cross examination by defense attorney Eric Nelson, Arradondo acknowledged that officers sometimes need to take control of a situation. “Would you agree that the use of force is not an attractive notion?” Nelson asked. In response, the Chief said, “I would say the use of force is something that most officers would rather not use, and agreed that department policy affords an officer flexibility under evolving circumstances for when to use force or choose to de-escalate an encounter with someone resisting arrest.

22. Katie Blackwell. (MPD Fifth Precinct Inspector). At the time of the Floyd killing, she  headed up training for the department. Blackwell was shown a photo from the viral video of Chauvin on Floyd’s neck and was asked whether that is a tactic the police are taught.”I don’t know what kind of improvised position this is,” said Blackwell.

She inspected  records showing the  training that Chauvin had received in 2016 and 2018, which included situations when a suspect is detained facedown and handcuffed. That training stated that officers should be careful when holding a handcuffed person on their stomach because that position makes it difficult to breathe and that the person should be put “in the side recovery position or an upright position … as soon as possible,” or run the risk of asphyxiation.

23. Ker Yang (MPD  Sergeant). Asa MPD crisis intervention trainer, Yang testified that listening is key to crisis intervention. Voice, neutrality, respect and trust are at the core of the model on how an officer should approach a crisis situation. “It is useful [and] it is practical,” he said. “When it is safe and feasible, we shall de-escalate.”

Yang coordinates with civilian mental health professionals to train officers who encounter people in crisis situations, such as mental health issues. Yang discussed the best practices in dealing with people in crisis, or a situation “beyond a person’s coping mechanism. When it is beyond their control, they don’t know what to do.” That could also include people under the influence of drugs and alcohol or suffering from anxiety. In such situations, officers are trained to “bring them back down.” When it is safe and feasible, we shall de-escalate,” and the model for crisis intervention focuses on voice, neutrality, respect and trust. “It is useful, and it is practical.”

On cross-examination, Yang agreed that officers in these situations are taking in a lot of information and processing it simultaneously.

24. Johnny Mercil (MPD Lieutenant). He is a MPD use-of-force trainer experienced in the martial arts, and one of his trainees was Chauvin. He testified that at the time of the Floyd encounter, the MPD had two permitted neck restraints: to render a suspect unconscious to counter “active aggression” and to keep a suspect conscious when offering the lesser “active resistance.” He said. “You want to use the least amount of force necessary to meet your objective to control. If those lower uses of force do not work or are too unsafe to try, you can increase your level of force against that person.

Mercil also testified about “red zones,” where injury tends to range from serious to long lasting and could include serious bodily injury or death. Such areas included the head, neck and sternum, among others.

On cross examination, Mercil admitted that sometimes a suspect will make excuses like being unable to breathe or having a medical emergency to try to avoid going to jail. He also admitted that there were some photos with Chauvin’s knee on Floyd’s back, not his neck and these were not neck restraints and that hostile bystanders could raise an alarm with officers.

25. Nicole Mackenzie (MPD Medical Support Coordinator & First Aid Educator). She is responsible for CPR and other classes for officers. She said police have a responsibility to both call an ambulance and render aid “if it’s a critical situation.” She testified that being able to talk doesn’t mean you’re necessarily able to breathe. She testified that agonal breathing, or a brainstem reflex that causes gasping, could be misinterpreted as breathing. “Somebody could be in respiratory distress and still be able to verbalize it,” she said. “Just because they’re speaking doesn’t mean they’re breathing adequately.”

She also said cardiopulmonary resuscitation (CPR) can be started by officers while waiting for paramedics to arrive and that officers are trained to do so while waiting for an ambulance. Talking doesn’t contradict someone’s contention that they can’t breathe.

However, she also admitted that chaotic scenes can adversely affect an officer’s ability to provide aid. “If you’re trying to be heads down on a patient that you need to render aid to, it’s very difficult to focus on that patient while there’s other things around you. if you don’t feel safe around you, if you don’t have enough resources, it’s very difficult to focus on the one thing in front of you.” But in response to questions by the State’s attorney, she said a crowd of agitated onlookers could excuse an officer from rendering aid “only if they were physically getting themselves involved.”

26.  Jody Stiger (Sergeant, os Angeles Police Department and use-of-force expert for the State of Minnesota. He reviewed the MPD use-of-force materials and testified that Chauvin’s use of force against Floyd was “excessive.” Initially when Mr. Floyd was being placed in the backseat of the squad car, the officers were justified in trying to have him comply and sit in the backseat of the vehicle. However, once he was placed in the prone position on the ground, he slowly ceased his resistance and the officers . . should have slowed down or stopped their force.”

Stiger testified that his review of all the video evidence showed that Chauvin had applied pressure to Floyd’s neck or neck area for 9.5 minutes from the time the officers put him on the ground with his hands cuffed behind his back until after the paramedics arrived.

The videos show Floyd being placed on his chest in the prone position. Stiger noted that he saw Floyd one time “kicked the officers’ arms in an attempt to possibly break free from the officers’ grasp.” This led the police to reverse their decision to use a hobble device on Floyd , which Stiger attributed to the officers recognition that Floyd was starting to comply and cease resistance. And that compliance and non-resistance continued through the remainder of Floyd’s time on the ground until he was taken on a gurney to the ambulance. In so doing, Chauvin put Mr. Floyd at risk of positional asphyxia or deprivation of oxygen.

Stiger said body-worn camera video from one of the officers showed Chauvin using “his right hand and appeared to use a pain compliance on Mr. Floyd’s hand.” Chauvin appeared to accomplish this by “squeezing [Floyd’s] fingers or bringing his knuckles together, which can cause pain or pulling the hand into the cuff, which can cause pain as well.”  Stiger also pointed out that “the handcuffs [on Floyd] were not double-locked [and as a result] can continue to ratchet tighter as the person moved.”

When someone cannot comply, he said, “at that point, it’s just pain.” He also testified that placing a person prone on the ground runs the risk of positional asphyxiation, and placing weight on that person heightens the risk.

Stiger concluded by saying that while the three officers were on Floyd, he “was not actively resisting while he was in the prone position” and , therefore, the amount of force by the officers was excessive.

Moreover, “as time went on . . .in the video you can clearly see that Mr. Floyd’s health was deteriorating, his tone of voice was deteriorating, his movements are starting to cease. As a police officer you realize something is not right . . . [which means you have a] responsibility to take some action [to improve the person’s condition].” But when Floyd kept saying, “my neck hurts, my back hurts, everything hurts,” all Chauvin does is utter “uh huh” and say “if Floyd can talk, he can breathe.”

Stiger also said  the officers also should have considered the nature of the original alleged offense when weighing use of force. In Floyd’s case, that was the passing of an alleged  counterfeit $20 bill at Cup Foods. Typically, for low-level offenses like this, “you wouldn’t expect to use any force.”

Under cross-examination, Stiger admitted every time an officer responds to a call there is an inherent risk. The bystanders’’ comments, Stiger said, were “potential threats,” but did not justify use of force.

27. James Ryerson (Special Agent, BCA). He described the BCA’s extensive investigation of the case–taking photos of Chauvin, processing videos and other evidence, including the squad and Floyd’s cars along with items subsequently found inside the vehicles: a pill, some dollar bills, a pipe.

 He testified that Chauvin kept his weight on a handcuffed George Floyd’s neck for minutes after Floyd was no longer talking or moving during the incident.

Under cross examination, Reyerson testified that a short clip of Kueng’s body cam video footage appeared to show Floyd’s saying, “”I ate too many drugs.”  But on redirect questioning, a longer version of the video was shown, and Reyerson said. “Yes, I believe Mr. Floyd was saying, ‘I ain’t do no drugs.'”

28. McKenzie Anderson (Forensic Scientist, BCA). She processed both Floyd’s car and Squad Car 320. On the latter, she tested eight stains, seven of them blood, that tested positive for George Floyd’s DNA. In January 2021, she reprocessed the two cars at defense attorneys’ request and found in the squad car what appeared to be a pill and pill remnants: in the center console of Floyd’s car were two small white pills; on the driver’s side floor was a box for Suboxone (a prescription medicine for adults with an opioid addition);  and on the driver’s side seat was an unopened packet of that prescription. The DNA on one of these pills matched Floyd’s DNA.

29.  Breahna Giles, (Chemical Forensic Scientist, BCA). She testified that the pills found inside Floyd’s car contained methamphetamine and fentanyl, both addictive opioids. The partial pill and other traces of it tested positive for methamphetamine, while another substance was detected on the largest partial pill, Defense attorney Eric Nelson asked Giles if the trace substance was fentanyl. “I can’t confirm if it was or was not fentanyl. A glass pipe in Floyd’s car tested positive for THC, the active ingredient in marijuana.

30.  Susan Neith (Forensic Chemist at NMS labs in Pennsylvania). She tested the two pills found in the Floyd car and the partial pill found in the squad car. All three pills contained a fentanyl concentration of less than 1%, which she said is common. The pills contained a methamphetamine concentration of 1.9 to 2.9%, which she said was atypically low. “The majority of the time I see 90 to 100% methamphetamine,” she said.

31. Dr. Martin Tobin (Chicago physician specializing in respiratory and Critical care and Expert Witness).“Floyd died from a low level of oxygen [that] caused damage to his brain . . .  [and] arrhythmia [pulseless electrical activity] causing his heart to stop.”

The low level of oxygen was due to “shallow breathing, small breaths . .  that weren’t able to carry the air through his lungs down to the essential areas of the lungs that get oxygen into the blood and get rid of the carbon dioxide..” All of this was due to his being “turned prone on the street,. . .  [having] handcuffs in place combined with the street, . . . a knee on his neck, and . . . a knee to his back and side.” Using a composite video, Dr. Tobin ”showed jurors how Floyd was positioned with the officers on top of him and how it contributed to his inability to take sufficient breaths.” Chauvin and officer Kueng “manipulated Floyd’s handcuffs by ‘pushing them into his back  and pushing them high, further hindering his ability to breathe.”

Floyd stopped breathing 23 seconds later and “didn’t have an ounce of oxygen in his body” less than a minute after losing consciousness, Tobin said. He noted the moment Floyd died when shown the bystander video of his final moments. “At the beginning you can see he’s conscious, you can see slight flickering and then it disappears, so one second he’s alive and one second he’s no longer,” Tobin said. ” … That’s the moment the life goes out of his body.” Yet after Floyd’s breathing ceased, “Chauvin’s knee remained on Floyd’s neck for another three minutes and 27 seconds.

Dr.Tobin continued, “ It’s like the left side is in a vise, it is being pushed in from the street at the bottom and the way the handcuffs are manipulated . . . totally interfere with central features of how we breathe. . . . Basically , on the left side of his chest, it’s as if a surgeon almost went in and removed the lung . . . and left him totally reliant on his right side.” In addition, Floyd was bracing his knuckles to try to get air. This shows he has used up all his resources and . . . is trying to breathe with his fingers and knuckles. . . . He is using his fingers  and knuckles against the street to try to crank up his chest. This is the only way to [try] to get air into the right lung.” 

In addition, the knee on Floyd’s neck also restricted “air getting into the passageway.” It was like “trying to breathe through a space similar to a small straw.” Yet Dr. Tobin saw no reduction in Floyd’s ability to breathe before he went unconscious.

Journalists, watching the trial, said, “Jurors paid close attention to Dr. Tobin’s testimony from start to finish, watching every video, chart or illustration, listening closely to his testimony, and taking notes at specific points.”

32. Daniel Isenschmid (Forensic Toxicologist at NMS Labs in Pennsylvania and Expert Witness). He testified that while fentanyl was found in Floyd’s blood, so was norfentanyl, which is metabolized fentanyl. Overdose victims rarely have norfentanyl in their blood, he said. He testified that Floyd’s ratio of fentanyl to norfentanyl was 1.96 ng/ml,compared with  the average ratio of 9.05 in postmortem cases and 3.2 in driving-under-the-influence cases. Floyd’s level of methamphetamine, 19 ng/ml, was in the bottom 5.9% of a sample of DUI methamphetamine cases. “Does this show Mr. Floyd was below the average and even below the median in DUI cases?” prosecutor Erin Eldridge asked. “Yes,” Isenschmid responded.

33, Dr. Bill Smock (Police Surgeon, Louisville Police Department and Expert Witness). He reviewed videos from Floyd’s arrest and other case records and concluded that Floyd died from positional asphyxia (a lack of oxygen) and not from a fentanyl overdose, which usually involves people who are sleeping, who snore and who have constricted pupils and falling breathing rate, none of which Floyd exhibited. Smock said Floyd was not snoring, had dilated pupils, and was talking and saying “I can’t breathe.” “That is not a fentanyl overdose,” he said. “That is someone begging to breathe.”

Smock also testified that Floyd also showed no signs at the scene of a diagnosis called excitable delirium, which is a “physical and psychiatric state “ when patients show a high heart rate, seemingly “superhuman strength,” garbled speech and other symptoms,

He also addressed Floyd’s need for CPR, “way before it was used. As soon as Mr. Floyd was unconscious, he should have been rolled over. … When they can’t find a pulse, CPR should have been started.”

34.  Dr. Lindsey Thomas (Retired Medical Examiner, Hennepin County Medical Examiner’s Office and Expert Witness).

She testified that “the primary mechanism of Floyd’s death was asphyxia, or low oxygen” and that “the activities of law enforcement officers resulted in Mr. Floyd’s death, and specifically their activities of subdural restraint and neck compression.”

All of these videos show that  this was not “a sudden death,” Thomas testified. “It’s not like snow shoveling when someone clutches their chest and falls over. There was nothing sudden about his death.” Nor was there any evidence he suffered from a heart attack.

She later said with certainty, “There’s no evidence to suggest he would have died that night except for the interactions with law enforcement.”

She said that the sheer volume of videos of Floyd’s death was “absolutely unique” in that she’d never had a case so thoroughly documented, and it helped her determine how Floyd died.

Dr. Thomas also explained that autopsy reports like the one by Dr. Andrew Baker, whom she had trained, have several categories for causes of death, and she agrees with Baker’s (a) listing “homicide” as the cause, meaning it was death caused by another human being; (b) listing Floyd’s health challenges and drug use as valuable for public health purposes although not a direct cause of death; and (c) not listing asphyxia as there is no test for oxygen in an autopsy.

35. Dr. Andrew Baker (Chief Hennepin County Medical Examiner).  He performed Floyd’s autopsy and stood by his opinion that Floyd’s cause of death was a homicide, caused by “cardiopulmonary arrest complicating law enforcement subdural, restraint, and neck compression.” Baker did not include a lack of oxygen, or asphyxia.

According to Baker, Floyd  had “a very severe underlying heart disease,” i.e., hypertension heart disease,” meaning his heart weighed more than it should. So he has a heart that already needs more oxygen than a normal heart by virtue of its size and it’s limited in its ability to step up to provide more oxygen to meet demand because of the narrowing of his coronary arteries.”

These heart conditions meant Floyd needed more oxygen, while faced with the challenge of being stressed by being pinned to the street with his face scraping the asphalt.

Floyd’s “being held to the ground . . . [[increasing] pain . . . for having [his] cheek up against the asphalt and that abrasion on [his] shoulder . . . are going to cause stress hormones to pour out of your body, specifically things like adrenaline, and what that adrenaline is going to do is it’s going to ask your heart to beat faster,” Baker testified. “It’s going to ask your body for more oxygen so that you can get through that altercation, and in my opinion, the law enforcement subdural restraint and the neck compression was just more than Mr. Floyd could take by virtue of those heart conditions.

Floyd’s health problem and drug use were not “direct causes. They are contributing causes.”

Baker saw no bruises or scrapes on Floyd’s neck or signs of pressure on the back of his neck and agreed with defense counsel that the pressure on Floyd’s neck “would not constrict his airway.”

Baker chose not to look at the videos of the police encounter before he completed the autopsy so as not to bias his findings.

Baker admitted he is not an expert on lack of oxygen because he does not treat live people and would defer to experts on same.

According to Ted Sampsell-Jones, a law professor at Mitchell-Hamline School of Law, “evidence about Floyd’s cause of death is shaping up to be the biggest weakness for prosecutors.” But the prosecution for  the charges against Chauvin only has to prove that Chauvin’s conduct was a “substantial contributing cause” for the death.


[1] See these posts fo Derek Chauvin Trial: Week One (Mar. 15, 2021); Derek Chauvin Trial: Week Two (Mar. 21, 2021); Derek Chauvin Trial: Week Three (Mar. 24, 2021); Derek Chauvin Trial: Commendations and Thank You’s (Mar. 25, 2021); Derek Chauvin Trial: Its National and International Importance (Mar. 28, 2021); Derek Chauvin Trial: Week Four (April 2, 2021); Derek Chauvin Trial: Week Four (Commentaries) (April 5, 2021); Derek Chauvin Trial: Week Four (Sources) (April 6, 2021). See also List of Posts to dwkcommentaries—Topical: George Floyd Killing,


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As a retired lawyer and adjunct law professor, Duane W. Krohnke has developed strong interests in U.S. and international law, politics and history. He also is a Christian and an active member of Minneapolis’ Westminster Presbyterian Church. His blog draws from these and other interests. He delights in the writing freedom of blogging that does not follow a preordained logical structure. The ex post facto logical organization of the posts and comments is set forth in the continually being revised “List of Posts and Comments–Topical” in the Pages section on the right side of the blog.

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