CrystalG,
I would call the cops and tell the 911 operator to send stern cops. Usually, when the operator hears that it's a kid, s/he'll send cops with-a background in mental illness or something, and they talktalktalk.

You need to scare your kid. He needs to know that it is not a joke. Do you have any friends who are cops? Anyone who can set up something?
I agree with-Insane. 11 is a hard age. No one wants to arrest such a little kid. (Except for weird stories you read about Florida!)
When my son was 10 or 11 (I don't remember now) I took him to juvenile detention and had the director give him a tour. On the way home difficult child said, "I know you would never send me somewhere like that. Because you love me."
I told him, "Just the opposite. Because I love you, I would make sure you went there if you broke the law and were convicted and sentenced. Because I love you, I will teach you consequences."
If he thinks that something is a joke, you have to up the ante. Our therapist told us to keep upping it until we get to a point where difficult child notices. If that means taking away his clothes (except for one outfit to wear the next day), do it. Is he staying up at night playing video games? The games go away. Lock them up somewhere so he can't see them. The lightbulbs come out of the sockets in his room. He's sneaking out? Get a camera--better yet, an alarm system--and catch him in the act. You'll lose sleep for a few nights waiting (although he probably has a pattern) but it's worth it. And make a big, hairy deal out of it.
Conversely, if he does something good, tell him right away.
Can you tell me where your first notes are here? I can't remember what he was like as a baby, if he has any hoarding habits, if he has texture issues or if there is something in the family tree you know about.