Key Moments on Day 9 of the Derek Chauvin Trial

A pulmonologist testified that George Floyd died “from a low level of oxygen,” and that being handcuffed and having knees on his neck and back contributed to his shallow breathing.,


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The trial of the former officer Derek Chauvin will continue on Thursday after a day of testimony focused on Mr. Floyd’s drug use on the day of his death. Mr. Chauvin’s defense has tried to argue that Mr. Floyd died from a possible overdose, but the prosecution blames the actions of Mr. Chauvin, who pinned Mr. Floyd with his knee for about nine and a half minutes.

Here are some key takeaways from recent testimony.




Pulmonologist Says George Floyd Died From a ‘Low Level of Oxygen’

Dr. Martin J. Tobin, a world-renowned expert on breathing, testified on Thursday that George Floyd died from a “low level of oxygen.” His testimony also highlighted how force from Derek Chauvin’s knee and Mr. Floyd’s position on the concrete obstructed Mr. Floyd’s airways.

“So let’s talk about your opinions with respect to this case, have you formed an opinion to a reasonable degree of medical certainty on the cause of Mr. Floyd’s death?” “Yes, I have.” “Would you please tell the jury what that opinion, or opinions, are?” “Yes, Mr. Floyd died from a low level of oxygen, and this caused damage to his brain that we see. And it also caused a P.E.A. arrhythmia that caused his heart to stop. The cause of the low level of oxygen was shallow breathing, small breaths, small tidal volumes, shallow 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 — that’s the alveoli at the bottom of the lung. The main forces that are going to lead to the shallow breath are going to be that he’s turned prone on the street, that he has the handcuffs in place combined with the street, and then that he has a knee on his neck, and then that he has a knee on his back and on his side. All of these four forces are ultimately going to result in the low tidal volume, which gives you the shallow breaths that we saw here. And so the air will not be able to reach those air sacs — we just saw in the video where the oxygen is exchanged and the carbon dioxide is removed. What you’re seeing is the orientation of Officer Chauvin, his body build is quite erect here. But in particular, what you’re seeing is that the toe of his boot is no longer touching the ground. This means that all of his body weight is being directed down at Mr. Floyd’s neck.”

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Dr. Martin J. Tobin, a world-renowned expert on breathing, testified on Thursday that George Floyd died from a “low level of oxygen.” His testimony also highlighted how force from Derek Chauvin’s knee and Mr. Floyd’s position on the concrete obstructed Mr. Floyd’s airways.CreditCredit…Still image, via Court TV

A veteran lung doctor testified on Thursday that George Floyd’s death was caused in part by Derek Chauvin’s knees pressing against his neck and back, making it impossible for him to breathe, and that Mr. Floyd showed signs of a brain injury about four minutes before Mr. Chauvin lifted his knee from his neck.

Dr. Martin J. Tobin, a pulmonologist and critical care doctor in Chicago, said in court that the combination of Mr. Chauvin’s pressure, the handcuffs pulling Mr. Floyd’s hands behind his back and Mr. Floyd’s body being pressed against the street had caused him to die “from a low level of oxygen.”

The testimony from Dr. Tobin on the ninth day of the trial of Mr. Chauvin, the former Minneapolis police officer who has been charged with murdering Mr. Floyd, signaled a shift into a new phase of the trial in which medical testimony will be key. Mr. Chauvin’s lawyer has suggested that Mr. Floyd died from the fentanyl and methamphetamine that were found in his system, but prosecutors argue that Mr. Chauvin had killed him by kneeling on him for more than nine minutes and cutting off his air supply.

Dr. Tobin was adamant that Mr. Chauvin had caused Mr. Floyd’s death on May 25. He said that based on Mr. Floyd’s visible respiratory rate before he went unconscious, any fentanyl in his system was “not having an effect” on his breathing.

“A healthy person subjected to what Mr. Floyd was subjected to would have died,” Dr. Tobin said.

After analyzing videos of the arrest, Dr. Tobin said he determined that Mr. Chauvin had pressed his left knee on Mr. Floyd’s neck for more than 90 percent of the time that Mr. Floyd was on the ground, and that he had kept his right knee on Mr. Floyd’s back for the majority of the time as well. That pressure, combined with having his hands cuffed behind his back and pushed into the street facedown, had cut off oxygen and caused his heart to stop, Dr. Tobin said.

“He was being squashed between the two sides,” he said.

Mr. Floyd was so desperate for air at one point that he tried to lift himself off the ground by pushing his right knuckle against a police car’s tire, Dr. Tobin said.

“This is his only way to try to get air into the right lung,” the doctor said.

Dr. Tobin, who works in pulmonology and critical care at Edward Hines Jr. Veterans Affairs Hospital and at Loyola University’s medical school, spoke for more than two hours to jurors. He said he had asked not to be paid when prosecutors asked if he would testify in the case. At several points, he encouraged jurors to feel parts of their own necks to demonstrate what he was saying; most of them followed along.

Dr. Tobin outlined four factors that he said had caused Mr. Floyd to lose oxygen and die: The left knee of Mr. Chauvin on Mr. Floyd’s neck, Mr. Chauvin’s right knee on Mr. Floyd’s back and side, Mr. Floyd being handcuffed as he was lying in the street, and Mr. Floyd being held in the prone position. These factors had combined to only allow Mr. Floyd to take small breaths, which were not enough to bring air to the parts of the lungs that allow oxygen to get into blood.

He said Mr. Floyd’s death could be called “asphyxia,” which he said is just another word for oxygen deprivation; a prosecutor told jurors when the trial began that Mr. Floyd died of asphyxia.

At one point in a video of Mr. Floyd’s arrest, Dr. Tobin noted, Mr. Chauvin’s left foot appeared to raise off the ground, which the doctor said meant that half of Mr. Chauvin’s body weight was pressing on Mr. Floyd’s neck.

After about 4 minutes and 51 seconds, Dr. Tobin said, Mr. Floyd stopped speaking or groaning. After just over 5 minutes, Mr. Floyd appeared to straighten out his legs, which Dr. Tobin said was a signal that Mr. Floyd was having a type of seizure because he had suffered a brain injury from the oxygen deprivation.

The doctor said the handcuffs were also an “extremely important” factor in Mr. Floyd’s death because Mr. Chauvin and another officer had pushed his hands upward and against his back, pressing his chest against the hard street.

“When you’re turned prone and with the knee on the back, now the work that Mr. Floyd has to perform becomes huge,” Dr. Tobin said, adding: “He has to try to lift up the officer’s knee with each breath.”

On Wednesday, a use-of-force expert, Sgt. Jody Stiger, who works with the Los Angeles Police Department Inspector General’s Office, testified that “no force should have been used” once Mr. Floyd was subdued, handcuffed and facedown on the pavement. The sergeant also said that Mr. Chauvin put Mr. Floyd at risk of positional asphyxia, or a deprivation of oxygen.

“He was in the prone position, he was handcuffed, he was not attempting to resist, he was not attempting to assault the officers — kick, punch, or anything of that nature,” Sergeant Stiger told prosecutors.

Responding to questions from the defense, Sergeant Stiger said that Mr. Floyd resisted arrest when officers tried to put him in the back of a squad car. In that moment, Mr. Chauvin would have been justified in using a Taser, Sergeant Stiger said.

Asked to interpret footage from a police body camera on Wednesday, Senior Special Agent James D. Reyerson of the Minnesota Bureau of Criminal Apprehension initially said Mr. Floyd appeared to say, “I ate too many drugs.” But in later testimony, Mr. Reyerson changed his assessment and said Mr. Floyd had actually shouted, “I ain’t do no drugs.”

His revised judgment could chip away at Mr. Chauvin’s defense, which has tried to argue that Mr. Floyd died from complications of drug use, not the actions of Mr. Chauvin. A toxicology report found methamphetamine and fentanyl in Mr. Floyd’s system.

McKenzie Anderson, a forensic scientist with the Minnesota Bureau of Criminal Apprehension, processed the squad car that Mr. Floyd was briefly placed in on the night he died. An initial processing found no drugs in the vehicle, she said, but during a second search requested by Mr. Chauvin’s defense team in January, the team discovered fragments of pills with DNA matching Mr. Floyd’s.

Breahna Giles, another forensic scientist with the Minnesota Bureau of Criminal Apprehension, testified that some of the pills recovered at the scene were tested and found to contain methamphetamine and fentanyl. They were marked with letters and numbers that indicate pharmaceutical-grade acetaminophen and oxycodone, though illicit pills are sometimes marked by drug dealers to give the false impression that they came from a pharmacy.

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