MINNEAPOLIS (AP) — Prosecutors on Wednesday filed a tougher charge against the police officer at the center of the George Floyd case and charged three other officers, delivering a victory to protesters galvanized by a death that roused racial tensions and unleashed coast-to-coast unrest.The most serious charge was filed against Derek Chauvin, who was caught on video pressing his knee to Floyd’s neck and now must defend himself against an accusation of second-degree murder.