I Think I Made A Greifer Mad...Are His Friends Coming After Me?

I met a guy a few days, he was nice, but immature. And a newbie. I didn't think much of it, since most of newbies I meet there are immature. I let him make me his friend.
The rest of the night and part of the next he offered me a few TPs to houses he had set up and would ask me to come join him, etc. I still thought nothing of it, although I wondered if he had permission to set up the houses after he tried to set one up in an outdoor store. One had been in a sandbox, the other on a large plot of land, I gave him the benafite of the doubt and didn't ask about the second (going back on it I know I should have).
Anyway, I had turned down a couple of his TPs yesterday because I was busy. I was running late to an event and he wanted me to go somewhere with him, so I TPed him to the event instead. (Please rememeber, I had no idea he was a greifer at this time.)
He didn't actually do anything last night. He kept leaving and coming back. A third of the way through the event he asked the owner of the sim if he would like to be sponsered and the owner politely refused. He left and came back a while later and came over to where I was sitting. He IMed me, claiming he was an assassin, and that he was going to shoot the owner. I told him he wasn't and IMed the owner when he left again. He didn't come back that night. I muted him.
So this morning, I'm playing Slingo. He shows up, sits at the top of the score board trying to get this one guy's attention, and shooting at people. He set off some kind of fireworks before the host kicked him out.
I took him off my friends list (which is how he found me after I muted him?). But about an hour ago, I was at a sim, and this guy in suit simmilar to the one he always wore showed up stood a few yards away from where I was. It was creepy, he didn't behave like the usual gawkers that show up at those places. When I moved toward him (not to confront him, I was going in a room near where he was), he dissapeared.
I went to my apartment to change clothes and there was a furry in a jumpsuit standing outside the door who disspeared before I could say anything to her. To get to my door you either have to TP from the lobby or my profile. It's unusal to even see other residents at my building.
In short, I think I'm on this hit list he mentioned.
Exactly what should I do about these guys...being creeped out alone isn't enough to report someone? If anyone has any experience with these guys, do they know what's comming or going on? What's the best / quickest way to get rid of them?

Edit: Just found an invisible prim owned by a female furry at my buisness. Couldn't get a ahold of it to figure out what it was, so I went ahead and returned it.
Edit: Was using the wrong word.

Sounds like you found a real nutcase, sorry for your woes. More than likely the female furry is using your apt when your not around, we do condo rentals here, and we see this sometimes happen. All you can do is file an abuse report if he continues to stalk you, and then call for Live Helper if he wont leave you alone. Good luck...hope he just dissapears

If you're worried about your apartment - get a security orb (if you can deed objects to the group that the land is owned by) - this will let you banish people from your home reliably.
If you can't do that, get the Visitor Master object from SpankMe Pinkerton's store. This will let you track who is using your space.