Wow, you are really grasping. Again, I'll note for you my point- it would seem that the police erred by not conducting a more thorough search of the vehicle. If you mean to ask about other cases in all recorded history, then the answer to your strawman of a question is, as you are aware, there are unsolved cases and each case depends on variables that the police should thoroughly investigate.
Which sat in the front yard of the mother's house, unlocked, for the whole world to search, including the mother.
They probably never expected the kids to be IN THE %#$$@ FRONT YARD FIVE FEET FROM WHERE THEY WERE SPEAKING WITH THE %#&^@ MOTHER!!!!
Are you saying the cops are more responsible for this tragedy than the mother?