On another session of Derek Chauvin's trial, a respiratory doctor said Thursday that George Floyd died from lack of oxygen and that the police officer's knee was on his neck almost all the time he was facedown with his hands cuffed behind his back. 

"Mr. Floyd died from a low level of oxygen," Martin Tobin, a pulmonologist who treats patients in a Chicago hospital's intensive care unit, told the jury in his testemony, confirming the county medical examiner's finding that Floyd's death was a homicide at the hands of police.