No there is not a world of difference, so many say they would jump in the car and go over there etc. dial 999 whatever. Nobody knows what they would do in any circumstance until they are in it. That is a fact, you have just stated it yourself in a post but now are denying it because it doesn't suit your theory. Sorry scipio but you can't have it both ways, I am not saying this to prove me right or because of any theory I may have and you are wrong, I am saying it because it's fact imo whether he killed them or not.
If my parents called claiming my brother was running around with a gun I KNOW I would do one of the following:
1) go over with on of my own weapons
or
2) call 911 telling them the situation and that I am going there with my gun so they are aware of wha tis going on
or
3) call 911 and go over without a weapon to be there to see what happens if not assist the police in some way such as trying to talk my brother out.
I know I would not do nothing. I know I would go over there or call 911 and go over.
I can't be sure whether I would go inside or not (it would depend on the exact circumstances encountered) but I know I would go over there to see what happens to my parents. Even if I thought I could handle it myself I would I know I would be inclined to call 911 anyway because I want them alerted in case I did get hurt or in case I had to hurt someone so that they would be aware why and would have help on the way just in case it was needed.
Calling a girlfriend instead of getting dressed and rushing over or instead of calling 911 would not cross my mind. Nor would I waste time looking up police numbers in a phone book. My township has its own police station but the main line is not for emergencies you call 911 for emergencies. This is common sense.
What one will do when faced with a moral dilemma is different.