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Chauvin trial: Expert says George Floyd died from 'a low level of oxygen' caused by cuffs, position

Dr. Tobin
Posted at 5:27 AM, Apr 08, 2021
and last updated 2021-04-08 18:29:11-04

MINNEAPOLIS — A key prosecution witness told jurors Thursday that George Floyd died due to a lack of oxygen from being pinned with a knee of his neck, and refuting the defense's claim that health concerns and pre-existing conditions contributed to Floyd's death.

Dr. Martin Tobin, a lung and critical care specialist at the Edward Hines Jr. VA Hospital and Loyola University’s medical school in Illinois, testified that because his breathing was severely constricted while Chauvin and two other Minneapolis officers held Floyd down, that due to a lack of oxygen, he suffered brain damage which then caused his heart to stop.

During his testimony, Dr. Tobin said Floyd died from a low level of oxygen, what some people may call asphyxia.

When asked by prosecutors what may have caused the lack of oxygen, Tobin said in his opinion "the cause of the low level of oxygen was shallow breathing."

Tobin added that if the heart disease was causing trouble breathing, Floyd would "have been complaining of chest pain, or have rapid breathing." Which, Tobin said, Floyd is not recorded as doing.

Another witness for the prosecution, Dr. Bill Smock, a forensic toxicology expert testifying for the state of Minnesota, stated during his testimony that "there was no evidence at autopsy that George Floyd had a heart attack."

Dr. Smock added that he did not see any evidence that Floyd died of a meth overdose and separate fentanyl overdose.

When asked if he saw any evidence of low oxygen on autopsy, Dr. Smock responded: "only his death, sir."

WARNING: The video clips above and in this story contain language and descriptions of situations that may be disturbing to read or hear.

Chauvin's trial will continue Friday morning at 9:15 a.m. ET.

Below is a live blog of Thursday's court proceedings.

Court TV will be the only network with cameras in the courtroom and will provide live, gavel-to-gavel coverage.

The entire trial will be on live TV as well as available online at CourtTV.com, and the Court TV app for Roku, Apple TV, Amazon Fire TV, and Android and Apple devices.

UPDATE, 6:15 p.m. ET: Dr. Bill Smock, a forensic toxicology expert testifying for the state of Minnesota, said during his testimony that "there was no evidence at autopsy that George Floyd had a heart attack."

UPDATE, 5:45 p.m. ET: Dr. Smock said during his testimony that as we see George Floyd's voice get weaker and weaker, his facial expression changes.

Dr. Smock said Floyd's brain was going without oxygen and you can hear the handcuffs shake as Floyd has an anoxic seizure.

UPDATE, 5 p.m. ET: Dr. Smock, takes the stand.

Dr. Smock said Floyd died from positional asphyxia, which he said is "a fancy way of saying he died because he had no oxygen left in his body."

“When the body is deprived of oxygen, and in this case from pressure on his chest and back, he gradually succumbed to lower and lower levels of oxygen until it was gone, and he died,” said Dr. Smock.

Dr. Smock said he did consider other causes of death for George Floyd, including “excited delirium,” which was dismissed. Excited delirium is characterized by agitation, aggression, acute distress, and sudden death, often in the pre-hospital care setting, according to the National Center for Biotechnology Information.

WATCH coverage of the Derek Chauvin trial HERE

UPDATE, 3:30 p.m. ET: Dr. Daniel Isenschmid, a forensic toxicologist at NMS Labs in Pennsylvania, took the stand. After being questioned by prosecutor Erin Eldridge, he said he reviews thousands of cases of year, including the George Floyd case.

Isenschmid said he tested sampled labeled as “hospital blood” and urine that was tested at Floyd's autopsy.

“The most notable findings in the hospital blood was the presence of fentanyl at 11 nanograms per milliliter and then the metabolite of fentanyl, the breakdown product of fentanyl, nor-fentanyl, at a concentration of 5.6 nanograms per milliliter. In addition, we found methamphetamine at 19 nanograms per milliliter,” said Isenschmid.

Isenschmid said that's a low level of methamphetamine consistent with a prescription dose.

He said methamphetamine is a central nervous system stimulant that can be prescribed under the brand name Desoxyn, which can be used for ADHD or obesity. He said methamphetamine can be a street level drug and a prescription drug.

Isenschmid said Floyd’s ratio of fentanyl to norfentanyl was below the median level in DUI cases.

UPDATE, 2:30 p.m. ET: Following a lunch break, defense attorney Eric Nelson cross examined Dr. Martin Tobin.

Under questioning from Nelson about clarifying what the low level of oxygen caused in Floyd's body, Tobin clarified that both the brain and heart were affected when the oxygen supply was closed off.

The defense has argued that health concerns and pre-existing conditions contributed to Floyd's death. Floyd's medical records indicated heart disease.

Tobin said if the heart disease was causing trouble breathing, Floyd would "have been complaining of chest pain, or have rapid breathing." Which, Tobin said, Floyd is not recorded as doing.

Nelson also asked how Floyd's previous COVID-19 diagnosis may have affected his breathing. Pointing out that people being treated for the virus are put in the prone position. He also asked about the impacts of fentanyl, methamphetamine, and adrenaline on the respiratory rate.

Tobin said these factors did not have any effect on Floyd's cause of death. He said even though people can die from fentanyl overdoses because of a low level of oxygen, they go into a coma first, and he said Floyd did not do that.

Under re-questioning from prosecutors, when asked about why there was an absence of bruising on Floyd's neck, Dr. Tobin said it was because it was a "static force." He compared it to going to church each week and sitting on a hardwood pew, "I don't have a bruise on my buttocks each week," he said.

Dr. Tobin describes the affect handcuffs had on George Floyd's breathing

UPDATE, 10:30 a.m. ET: An expert on pulmonology and critical care was called to the stand by the prosecution.

Dr. Martin Tobin said George Floyd died from a low level of oxygen, what some people may call asphyxia. When asked by prosecutors what may have caused the lack of oxygen, Tobin said in his opinion "the cause of the low level of oxygen was shallow breathing."

He explained that oxygen was not able to reach the lower parts of the lungs because of the shallow breaths Floyd was taking. This caused damage to Floyd's brain and heart.

The defense has argued Floyd's death was caused by a combination of drug use and medical conditions.

Tobin said Floyd being in handcuffs, lying in the prone position, having a knee on his back with an arm on his side, and having pressure on his neck all contributed to him having to take shallow breaths, which led to his death.

He said the handcuffs were pushed into Floyd's back, while being pushed down on a "hard street." Tobin said the maneuver puts Floyd's body in a type of "vise."

He said that positioning "interferes with central features of how we breath."

Tobin said he had seen video of the May 25, 2020 incident, and said under the first few minutes of being restrained, "we know that his oxygen levels were enough to keep his brain alive because he continued to speak and made sounds for 4 minutes and 51 seconds."

He said when Chauvin lifted his toe off the ground, as he said he saw in the video, he was putting more pressure on Floyd's neck.

The doctor said there was movement in Floyd's leg that shows, in his opinion, Floyd suffered a brain injury from suffering a low level of oxygen.

Tobin pointed out that a person lying on their stomach, with an arm raised behind their back, as Floyd did when his hands were handcuffed, would have to work harder to breath because of the natural pressure on the lungs and breathing.

Floyd had underlying health conditions, and the defense has argued these contributed to his death.

Tobin said it was his opinion that a healthy adult, with no underlying health concerns, would also likely have died if they were subjected to the same kind of pressure Floyd was subjected to.

The doctor said fentanyl lowers the respiratory rate when people take the drug. According to video of Floyd's arrest and death, Tobin said his respiratory rate was normal, the rate was 22, when fentanyl would have made it around 10.

WATCH coverage of the Derek Chauvin trial HERE

Court TV will be the only network with cameras in the courtroom and will provide live, gavel-to-gavel coverage. The entire trial will be on live TV as well as available online at CourtTV.com, and the Court TV app for Roku, Apple TV, Amazon Fire TV, and Android and Apple devices.

Find Court TV's full coverage of MN v. Derek Chauvin here.

Original story below

MINNEAPOLIS — The placement of former officer Derek Chauvin's knee on George Floyd and a statement Floyd made to officers became the focus of testimony Wednesday, even as prosecution witnesses started getting more technical about the investigation into Floyd's death. Thursday's court proceedings are expected to being just after 10 a.m. ET.

Chauvin is facing second- and third-degree murder charges for the May 25, 2020 death of Floyd. Bystanders outside the Cup Foods in Minneapolis captured the scene on video, which was widely shared on social media and showed Chauvin on top of Floyd's neck and back for almost nine minutes.

A use-of-force expert and a state investigator told a Minneapolis court Wednesday it appears to them Chauvin had his knee on Floyd's neck area the entire time he was handcuffed and lying facedown on the ground. The defense has questioned witnesses, showing still images from body-worn police officer cameras from different angles, asking if it appears Chauvin's knee is on Floyd's shoulder blade, and not his neck.

Defense attorney Eric Nelson introduced images from a training document that seemed to show a maneuver that included an officer placing a knee on a subject upper back.

Sergeant Jody Stiger, a prosecution expert witness who is with the Los Angeles Police Department, said in his expert opinion, “no force should have been used” on Floyd after he was handcuffed and on the ground, because of the risk of injury or death. He also repeatedly answered that he believed Chauvin’s knee was on Floyd’s neck, “above the shoulder blade,” he told Nelson.

A statement that was echoed by Minnesota Bureau of Criminal Apprehension special agent James Reyerson.

He testified that in his opinion, and as part of the investigation he led, Chauvin's knee "appears as though it's on the back of Mr. Floyd's neck."

Nelson also questioned Stiger and Reyerson about a short 10-second clip of body-worn camera footage that included a muffled statement from Floyd. Stiger, said the audio was not clear enough to make out.

Nelson asked Reyerson if it was possible Floyd said “I ate too many drugs.”

Reyerson responded it was possible.

However, he was brought back to the stand after allowed to watch a longer clip of the segment in context. He said it sounded more like Floyd responding to officers’ questions about whether he was on drugs with “I ain’t do no drugs.”

Prosecutors also called forensic scientists to the stand, who said there were pills found in both the squad car and the SUV Floyd arrived to Cup Foods in. They testified that the pills did contain methamphetamine and fentanyl.

WATCH coverage of the Derek Chauvin trial HERE

Court TV will be the only network with cameras in the courtroom and will provide live, gavel-to-gavel coverage. The entire trial will be on live TV as well as available online at CourtTV.com, and the Court TV app for Roku, Apple TV, Amazon Fire TV, and Android and Apple devices.

Find Court TV's full coverage of MN v. Derek Chauvin here.