The Washington PostDemocracy Dies in Darkness

Experts in Chauvin’s trial challenge defense’s case for what killed Floyd

Martin Tobin, a pulmonologist from Hines, Ill., said on April 8 that George Floyd died of lack of oxygen, which did not result from a fentanyl overdose. (Video: The Washington Post)
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A breathing expert said that George Floyd died of low oxygen, struggling for air under an officer’s knee. A police surgeon emphatically discounted that Floyd suffered a heart attack or had “excited delirium,” and a forensic toxicologist said Floyd’s blood contained only a small amount of methamphetamine.

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Thursday’s testimony in the murder trial of former Minneapolis police officer Derek Chauvin spoke to what could be the heart of the case, challenging the defense’s central argument that Floyd died of a combination of heart disease, drugs and high blood pressure. Chauvin’s attorney has suggested Floyd’s already-compromised heart grew overwhelmed by his struggle with Minneapolis police. Andrew Baker, the chief medical examiner in Minnesota’s Hennepin County, is expected to testify Friday.

Here’s what to know:

  • Asked when authorities should have performed CPR on Floyd, police surgeon Bill Smock responded: “Way before it was. As soon as Mr. Floyd is unconscious, he should have been rolled over.”
  • Martin Tobin, a pulmonologist and breathing expert, said a person in good health would have died as a result of the restraint administered by Chauvin. He estimated that Chauvin placed more than 91 pounds on Floyd’s neck.
  • Floyd’s airways were 85 percent restricted, Tobin said, thus making breathing “at some stage unsustainable.”
  • Chauvin attorney Eric J. Nelson again focused on the traces of fentanyl and methamphetamine that were found in Floyd’s body, in an effort to show they were a contributing factor to his restricted breathing.