You are correct that we do not have a mind reading machine so it cannot be 100% proven, that doesn’t make it not true.
I've made it pretty clear that Im not certain of his state of mind, by saying he only probably didn't go with an intent to shoot people. Maybe that is even unfair, but I tend to think people are more likely to be motivated stupidity rather than motivated by malice.
You seem to be criticizing your own position here because you are the one defending your claim that you know what his state of mind was, and appear to be assuming, because I disagree with you, that I must be taking the exact opposite position and assuming that I know he had no intent to shoot people.
further expanded that even if someone were to accept your argument that he didn’t that doesn’t mean he’s innocent of his actions.
Sure, and I followed this up with some more questions as to what was the crime. It would have also gone a long way to ease the debate if you had said you were no longer talking about intent (especially because you kept repeatedly saying that intent did not matter) and had moved on to a new way to try and claim you know he was guilty.
Vigilantism. “The laws / legal system are insufficient” is not a defense of immoral, dangerous, or damaging behaviour.
Which law exactly? Why wasn't he charged with it? If a shop owner stood there with a gun to protect their own property, is that illegal vigilantism? What if it is the shop owner and their family? Or friend? I'm curious to hear this line of reasoning, but it's a bit vague for me to really sink my teeth into.