It is? Why?
You are well within your rights to notice someone who is acting suspiciously in your neighborhood AFTER numerous home invasions have taken place (actually, even without the home invasions). You are well within your rights to follow him and tell the police his whereabouts. What is NOT legal is for that person to physical attack you because you are keeping an eye on him. That can get him shot.
Translation: You can roam your neighbourhood with a gun, stalk whomever you like, confront unarmed people for no reason, threaten them and when you consider you have had enough, just murder them and claim self defence, who's going to argue that right, you just shot and murdered the only witness.
Not hard to work out Zimmerpig Murdered another man, any way you cut it, he went looking for trouble, he found it, he murdered it!