How do they know????? Forensics...crime scene ananlysis! (And...don't ever lie after a shooting....or you are already guilty of a serious crime....perjury. And it makes you appear guilty of much more!)

Even if they are scum....if you escalulate and or precipitate a confrontation...you have reduced or nullified your "legal" claim to self defense. You can go gather information.....you can inform someone they are trespassing...you can notify law enforcement....but you can not "instigate" a confrontation and expect a "sympathetic ear" from the grand jury on a claim of self defense.

Let law enforcement officers....enforce the law. (Or have a really "GOOD" lawyer on retainer...and pray for good luck!)