I'll try but I don't how this possibility can be so confusing to some.
Imagine you were the Lt.
Imagine that (who knows why?) you decided to fake a criminal encounter.
Imagine that you decided you wanted to make that encounter look like you were ambushed and stripped of your weapon.
Imagine that you decided to shoot yourself in the vest once or twice to make it look like your (imaginary) attackers got your gun away from you and then tried to kill you with it.
Imagine the first shot to your vest went as well as expected.
Imagine you then walked about a hundred feet, doing various things to make it look like a struggle took place.
Then, imagine you intended to shoot yourself (in the vest) a 2nd time and this time in the chest.
You choose an odd angle to make it look more convincing.
Imagine you do all of this with no intention of injuring or killing yourself.
Then, imagine that 2nd shot goes horribly wrong and you are dead - despite your intentions.
Did that help?