Expert: Lack of oxygen killed George Floyd, not drugs

George Floyd died of a lack of oxygen from being pinned to the pavement with a knee on his neck, medical experts testified at former Officer Derek Chauvin's murder trial, emphatically rejecting the defense theory that Floyd's drug use and underlying health problems killed him.

"A healthy person subjected to what Mr. Floyd was subjected to would have died," prosecution witness 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 on April 8.

Using easy-to-understand language to explain medical concepts and even loosening his necktie to illustrate a point, Tobin told the jury that Floyd's breathing was severely constricted while Chauvin and two other Minneapolis officers held the 46-year-old Black man down on his stomach last May with his hands cuffed behind him and his face jammed against the ground.

The lack of oxygen resulted in brain damage and caused his heart to stop, the witness said.

Tobin, analyzing images of the three officers restraining Floyd for what prosecutors say was almost 9 1/2 minutes, testified that Chauvin's knee was "virtually on the neck" more than 90% of the time.

He said several other factors also made it difficult for Floyd to breathe: officers lifting up on the suspect's handcuffs, the hard pavement, his prone position, his turned head and a knee on his back.

Chauvin kept his knee on Floyd's neck for 3 minutes, 2 seconds, after Floyd took his last breath, Tobin said. After that last breath, Floyd's oxygen levels went down to zero and Floyd "reached the point where there was not one ounce of oxygen left in the body," he said.

As prosecutors repeatedly played a video clip of Floyd on the ground,...