George Floyd asphyxiated in custody, doctor testifies in 3 ex-cops' federal trial

Updated 1:15 p.m.

The federal trial of three former Minneapolis police officers charged with violating George Floyd’s civil rights resumed Monday with a doctor testifying Floyd died due to asphyxia caused by then-officer Derek Chauvin’s knee on Floyd’s neck as the man lay handcuffed and face down on the ground.

Carbon dioxide levels in Floyd’s blood show that he died of asphyxia and not sudden cardiac arrest, said Dr. David Systrom, a pulmonary and critical care doctor who works for Brigham and Women's Hospital in Boston, which is associated with Harvard University.

Authorities fired Chauvin from the force and a jury later convicted of murder in Floyd’s killing while in police custody. He pleaded guilty to federal charges in December.

During Chauvin’s trial on state charges, Hennepin County Medical Examiner Andrew Baker testified the actions of Minneapolis police to restrain and subdue George Floyd as they tried to arrest him “tipped him over the edge” from life to death.

In the current trial, federal prosecutors charged Tou Thao, J. Alexander Kueng and Thomas Lane with failing to provide medical aid to Floyd. Thao and Kueng face additional charges of failing to intervene with Chauvin’s use of force on Floyd. The three were on the scene with Chauvin on May 25, 2020 outside Cup Foods in south Minneapolis.

Testifying for the prosecution, Systrom told the court there were two causes of Floyd’s asphyxia. One cause was obstruction to his breathing caused by Chauvin’s knee on his neck for more than nine minutes. Holding Floyd in the prone position on hard asphalt also didn’t allow Floyd to breathe adequately.

Systrom’s testimony covered Chauvin’s role in Floyd’s killing, but also that of the other officers.

He testified that Kueng holding Floyd’s wrist and putting pressure on his back would have prevented Floyd from adjusting to continue to breathe. He also said that Lane holding down Floyd’s leg would have prevented Floyd from changing positions so he could breathe better.

Asked why Floyd may have started saying he couldn’t breathe when he was in the squad, before he was on the ground, Systrom said shortness of breathe is a symptom of claustrophobia. Floyd told officers he was claustrophobic as they tried to get him in the squad.

He also noted that Chauvin had his arm across Floyd’s throat for about a minute and that, essentially, Floyd was being held a prone position in the squad, which would have made it hard to breathe.

Prosecutors also sought to counter the likely argument from defense attorneys that fentanyl in Floyd’s system contributed to his death.

Systrom testified that fentanyl overdoses cause breathing to slow, but that Floyd’s breathing was faster than normal. He said that someone having a fentanyl overdose would not say, “I can’t breathe.”

Even after Floyd’s heart stopped, immediate CPR would have doubled or tripled Floyd’s chance of survival, Systrom testified.

After four minutes without CPR, the chance of full recovery substantially decreases, he said. Systrom testified that there’s a 10 percent drop in chances for survival per minute, and that officers restrained Floyd for three minutes after his heart stopped.

The trial of the three ex-officers began with jury selection on Jan. 20. The judge has said he hopes to wrap the trial up within a month and has pushed prosecutors to avoid duplicative evidence.

Last week’s delay of testimony after a defendant tested positive for COVID-19 was the first COVID-related complication in the trial.  

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