Derek Chauvin is on trial for George Floyd's death

By Melissa Macaya, Mike Hayes, Melissa Mahtani, Veronica Rocha and Fernando Alfonso III, CNN

Updated 7:34 PM ET, Thu April 8, 2021
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1:42 p.m. ET, April 8, 2021

Bystander video shows "the moment the life goes out" of Floyd's body, pulmonary expert says

Dr. Martin Tobin, a pulmonary expert, testified that George Floyd's final moments of his life can be seen in the bystander video of the May 25, 2020 incident.

While reviewing the video in court in front of jurors, Tobin said, "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," the pulmonologist said.

"You can see his eyes, he's conscious, and then you see that he isn't. That's the moment the life goes out of his body," Tobin said.

Floyd, he said, struggled and tried to breathe as officers restrained him.

"You can see how he's moving his hip to try and rock the right side of his body to try and get air. You can see him again pushing down on the street to get air in. And there is movements of his hip. You may miss, but he's having to use all his internal spine to just try and get air into that right side of the body. Keep in mind the left side is nonfunctional from the way they have manipulated him and pushed him into the street so he's constantly, cranking up his right side of his body, you can see it right there to try and get some air into his right side of his chest. He's making repeated struggling movements. He's moving again the hips because he's using his spine to try and get them — those muscles to move air into the right side of his chest. And he's again trying to use his right arm and he's unable because of the chain, the small chain linking it over to the left side. He's trying to have pushed down on that right arm into the street to try and help him but he's unable to do it because of the chain on the handcuffs," Tobin said.

The expert said the restraints on Floyd continued even after he stopped breathing.

"No, the restraints continued after that — he has the cessation of respiratory efforts. When you last take a breath the knee remains on the neck for another 3:27 after he takes his last breath. There's the knee remains. After there's no pulse, the knee remains on the neck for another 2:44 after the officers have found themselves, there's no pulse, the knee remains on the neck another 2:44," Tobin said.

Watch Dr. Tobin's testimony:

12:50 p.m. ET, April 8, 2021

Pulmonary expert: The statement "if you could speak, you can breathe" is misleading


Prosecuting attorney Jerry Blackwell told Dr. Martin Tobin that the jurors may have heard one of the officers say, "if you could speak, you can breathe" during the trial. Blackwell asked Tobin, a pulmonary expert, if that is a true statement.

"It is a true statement, but it gives you an enormous false sense of security," he said.

Tobin added: "Certainly, at the moment that you are speaking, you are breathing. But it doesn't tell you that you're going to be breathing five seconds later." 

Tobin said that Floyd speaking during the incident was important to his analysis of the medical records in this case.

"Because it tells us that for the time that he is speaking, and he continues to speak for 4 minutes and 51 seconds from the time the knee is placed on his neck, and tells us that there could not have been completes compression," he said.

Asked by the prosecutor if the brain is sensitive to oxygen deprivation, Tobin said, "The brain is the most sensitive area to needing oxygen."


12:48 p.m. ET, April 8, 2021

A healthy person would have died under the same conditions, pulmonary expert says


Dr. Martin Tobin, a pulmonary expert, acknowledged that George Floyd had pre-existing conditions but said a healthy person would have died under the same conditions Floyd was subjected to.

The prosecutor asked Tobin if he had "an opinion of reasonable degree of medical certainty as to whether a person who had none of those pre-existing health conditions, a healthy person, would have died under the certain same circumstances of Mr. Floyd?"

Tobin responded:

"Yes. A healthy person subjected to what Mr. Floyd was subjected to, would have died as a result of what he was subjected to."

12:39 p.m. ET, April 8, 2021

Chauvin's knee remained on Floyd's neck for 3 minutes after his oxygen reached zero, expert says

Dr. Martin Tobin, a pulmonary expert who reviewed medical records in the case, testified that he determined that at one point while Derek Chauvin was on top of George Floyd there was "not an ounce of oxygen left in his body, in his entire body."

"There is not an ounce of oxygen left in his body. And again ... you can figure this out with very precise science, looking at once somebody stops breathing, what will be the rate of decline in oxygen, how long it will take to reach zero," Tobin said.

Asked if Chauvin removed his knee from Floyd's neck at the point that there was no more oxygen in his body, Tobin said, "No, the knee remained on the neck for another 3 minutes and 2 seconds, after we reached the point where there was not one ounce of oxygen left in the body."

12:28 p.m. ET, April 8, 2021

Pulmonologist: Floyd's lung volume decreased by 43% while Chauvin held him down

Dr. Martin Tobin, a pulmonologist who reviewed medical records in the case, testified that George Floyd's oxygen levels significantly decreased while ex-cop Derek Chauvin was on top of him.

"He has to try to fight against the small volumes he has, and he has to try to lift up the officer's knee with each breath," Tobin testified.

He continued that Floyd "has to try and also lift up the effect of the other officer pumping in his arm with a handcuffed arm. They are pushing it in, into his chest. So he has to make all of these efforts to try and breathe against that."

Tobin said that it was his analysis that Floyd saw a "43% reduction in his oxygen reserves." He testified that reduction was due to a drop of "24% from being prone and another 19 from the knee on the back." 

12:24 p.m. ET, April 8, 2021

Most jurors appear to be engaged and taking notes during pulmonologist's testimony

From CNN's Brad Parks

Dr. Martin Tobin testifies on April 8 at Hennepin County Courthouse in the trial of former Minneapolis police Officer Derek Chauvin.
Dr. Martin Tobin testifies on April 8 at Hennepin County Courthouse in the trial of former Minneapolis police Officer Derek Chauvin. Court TV/Pool/AP

Most jurors appear to be engaged and taking notes during testimony from pulmonologist Dr. Martin Tobin this morning in the Derek Chauvin trial, according to reports from two courtroom pool reporters. 

"The jurors and court seem attentive and engaged by the visual aids," according to one report. The reports say most of the jurors have been taking notes during Tobin’s testimony.

The reports also noted that almost all of the jurors followed along and did what the doctor asked when Tobin invited members or the jury to feel their necks during his testimony. After the judge told jurors they don’t have to follow the witness' instructions, most of the jurors continued to do it to themselves. 

As the doctor explained how officers Chauvin and J. Alexander Kueng were holding Floyd, "all jurors were watching the video, not taking notes," the report said.  

12:05 p.m. ET, April 8, 2021

Pulmonary expert: Floyd's leg shows evidence that he was having a seizure due to brain injury from low oxygen


Testimony has resumed at the Derek Chauvin trial and Dr. Martin Tobin, a pulmonologist, is still being questioned by the prosecution.

Tobin said that George Floyd's leg movements during the incident shows evidence that he was experiencing a seizure while Chauvin was holding him down.

"We see and we can tell from the movement of his leg that the level of oxygen in his brain has caused what we call a myoclonic seizure activity," he said.

"Those are medical terms but basically it means he has kicked out his leg in an extension form, that he has straightened out his leg, and that is something we see as clinicians in patients when they suffer brain injury as a result of a low level of oxygen." 

Tobin was asked if it is significant that Chauvin moved his knee off of Floyd's neck after he was unconscious.

He responded: "No. I mean, it — the movement happens around a different times but obviously the key thing is everything up to the time ... the brain injury that's occurring. And where officer Chauvin moved his knee after that really is not going to have material impact on the case."


11:54 a.m. ET, April 8, 2021

Court is back in session

Dr. Martin Tobin, a pulmonologist who reviewed medical records in George Floyd's case, has resumed his testimony after the court took a 20-minute break.

11:33 a.m. ET, April 8, 2021

The court is in a morning break

The court is in a 20-minute break.

Dr. Martin Tobin, a pulmonologist who reviewed medical records in George Floyd's case, will resume his testimony when the court returns.