The Minneapolis chief of police, Medaria Arradondo, also began to give evidence against Chauvin, who he fired shortly after Floyd’s death. Prosecutors said in their opening statement that Arradondo will say Chauvin used “excessive force” in the arrest that ended in Floyd’s death in May last year, and that his conduct was “not consistent” with Minneapolis police training. On Monday, they began by leading the chief through his lengthy career and experience. It is highly unusual for a police chief to give evidence against one of his own officers. Chauvin, 45, has denied charges of second- and third-degree murder, and manslaughter. He faces up to 40 years in prison if convicted of the most serious charge. Three other officers face charges.