Reports I’ve read said that the jury, after reviewing the law and all the evidence, unanimously decided that a murder conviction would not be lawful and then proceeded to discuss voluntary manslaughter. At the time of the mistrial, one jury member had already decided on acquittal and five of the jurors were undecided whether to convict Slager of anything.
Remember, there are circumstances in which it is legal for an officer to shoot a fleeing suspect. The Supreme Court, Tennessee vs Garner, said this: “The Tennessee statute is unconstitutional insofar as it authorizes the use of deadly force against, as in this case, an apparently unarmed, nondangerous fleeing suspect; such force may not be used unless necessary to prevent the escape and the officer has probable cause to believe that the suspect poses a significant threat of death or serious physical injury to the officer or others.”
IOW, to convict Slager, the prosecution had to prove BEYOND A REASONABLE DOUBT that Slager did NOT have probable cause to believe that Scott was “unarmed, nondangerous,” and “posed a significant threat of death or serious physical injury to the officer or others.”
It is easy for the casual TV viewer to criticize the actions of a jury of citizens and ascribe vile motivations to them. But those folks had the responsibility to decide the case and there is no reason to doubt their good faith.