Mistrial in Freddie Gray Case in Baltimore; Chicago Cop Faces Murder Charges in 16-Shot KillingLeid Stories returns to its series on killer cops with major updates on two cases—the death last April of Freddie Gray, 25, a week after suffering severe spinal injuries while being transported to a Baltimore police stationhouse after a contentious arrest, and the killing of 17-year-old Laquan McDonald on Oct. 20 last year by Chicago police officer Jason Van Dyke.A Baltimore judge declared a mistrial yesterday in the case against Officer William Porter, one of six officers charged in Gray’s death and the first to be tried, after a jury said it was hopelessly deadlocked in deciding four charges against him. In Chicago, Officer Van Dyke yesterday formally was charged with six counts of murder “The People’s Attorney General” Alton H. Maddox Jr., who had predicted that Porter would walk because of tactical and legal errors by the prosecutor, discusses legal problems with both cases.