But setting that aside, when you have no weapon, no gun residue, and no witnesses, how is a juror with reasonable doubt participating in a "miscarriage of justice?" With all the apparatus of the state at his disposal, the prosecutor could do no better than the case as brought. You can't simply assume that everyone with motive and opportunity is guilty of murder.
And because the drunk is dead, there will never be an investigation into the circumstances of the collision: did Barajas contribute to the accident that killed his sons by getting them to push an out-of-gas vehicle on a public right of way? Does that sound like a good parental decision to you? Would you let your small boys do that?