evidence: Former Minneapolis Police Officer Derek Chauvin's trial began Monday morning. Chauvin faces three charges, including second-degree murder, in the death of George Floyd. [...] Murder suspect Derek Chauvin "looked so comfortable" while putting "the majority of his weight" on top of George Floyd's neck, a firefighter testified. [...] George Floyd's nephew, Brandon Williams, said he walked out of the Hennepin County District Court's overflow room Monday when prosecutors showed a graphic bystander video during opening statements of Floyd pinned under Derek Chauvin's knee.