George Floyd died from a “low level of oxygen” after Derek Chauvin knelt on his neck, a medical expert testified on Thursday in the trial of the former police officer charged with the Minneapolis man’s murder.
One of the central questions in the trial, which has received global attention, is whether Chauvin caused Floyd’s death when he knelt on his neck for approximately nine minutes, or whether it was caused by a heart arrhythmia after Floyd ingested drugs, as the defence has asserted.
Dr Martin Tobin, a Chicago pulmonologist, took to the stand on Thursday morning to testify on behalf of the prosecution, telling jurors that Floyd died from “a low level of oxygen”.
“This caused damage to his brain that we see, and it also cause a [pulseless electrical activity] arrhythmia that caused his heart to stop,” he said. “The cause of the low-level of oxygen was shallow breathing.”
On cross-examination defence attorney Eric Nelson quizzed Tobin on multiple scientific points, with the doctor sometimes correcting him. Nelson tried to suggest that fentanyl could cause death through low oxygen to the brain. Tobin acknowledged that could happen, but not in the manner that he had observed with Floyd.
Chauvin and three other officers arrested Floyd on May 25 for allegedly using a counterfeit $20 bill. A bystander filmed Chauvin pinning a handcuffed Floyd to the ground with a knee on his neck and posted it online. Floyd’s death was seen as a symbol for how black Americans are treated by the police and set off protests worldwide against racial injustice.
In a country where officers are seldom convicted in on-duty killings, Chauvin has pleaded not guilty to charges of second- and third-degree murder, as well as manslaughter.
The video is now a crucial piece of evidence for prosecutors. They also have placed other Minneapolis police officers, including Medaria Arradondo, department chief, on the stand in an attempt to demonstrate that Chauvin used more force to subdue Floyd than department policy allowed.
Nelson said in his opening statement that Chauvin followed his training, and attempted to sow doubts with jurors about what actually caused Floyd’s death. The US legal system says a criminal defendant, presumed innocent, can be convicted only if prosecutors prove their case “beyond a reasonable doubt”.
But Tobin said the main factors that caused Floyd’s shallow breathing include that he was lying face down, wearing handcuffs, and that Chauvin had one knee on his neck and another knee on his back.
Prosecutors showed an image from the video where the toe of Chauvin’s boot is not touching the ground.
“That means all of his body weight is being directed down at Mr Floyd’s neck,” Tobin said.