The trial of former Minneapolis police officer Derek Chauvin continues on April 9 with key witness testimony. Chauvin, who was filmed with his knee on George Floyd’s neck in May, faces murder and manslaughter charges for the encounter that sparked months of historic protests around the world. This stream contains graphic content. Lt. Richard Zimmerman, the most senior officer in the Minneapolis Police Department, testified earlier that Chauvin’s use of force against George Floyd was “uncalled for” and “totally unnecessary.” Zimmerman said that once someone is handcuffed, “they are not a threat to you at that point” and the amount of force should be immediately reduced. “If your knee is on a person’s neck, that could kill him,” he testified. Eric Nelson, Chauvin’s attorney argued that police can use “improvisation” for “whatever force is reasonable and necessary. The Post’s Libby Casey will anchor live coverage featuring reporters Mary Beth Albright, Lenny Bernstein, Rhonda Colvin, Nicole Ellis, Hannah Jewell, Joyce Koh, Robert Samuels and Eugene Scott. Plus, columnist James Hohmann.