evidence: An unprecedented lineup of law enforcement officers – including the Minneapolis police chief – tookthe stand at the murder trial of former officer Derek Chauvin, denouncing him for kneeling on the neck of George Floyd for more than nine minutes. [...] Chauvin knelt on Floyd for nine minutes and 29 seconds, according to prosecutors. A renowned pulmonary critical care doctor testified Thursday that Floyd died from a "low level of oxygen" when Chauvin pinned him to the street and restricted his ability to breathe. [...] Correction: A previous version of this story misstated the charges Derek Chauvin faces in George Floyd's death. They are second-degree unintentional murder, third-degree murder and second-degree manslaughter. He has pleaded not guilty.