catch him and then ask him what hes doing.

i say purposefully plant something that you know he would go to
like a letter with some weird shit in it
that would get him freaked out
and then when he asks u about it just say u planted it there because u knew he would go through ur stuff and see it

im thinking something about aliens or some other really crazy scheme or plan
like a plot to take over the world
or a plot to hold ur family hostage and control their minds
or something really out there like that

that'll teach his little snooping butt a lesson lol

lol thats a good one!!!!! :p :D:D:D:D:D
that will freak him out..
well i dont really know what u should do, maybe just scare him and tell him that u know what he does, and that u can proove it and if he wont stop u ll tell ur parents. i think that will stop him...

one wuestion wut is usually missing?

scaring him would indeed be a funny way to solve your problem...

but, he is 12 and he's probably gonna stop it soon anyway. if i had to do somethin about it, i would go with the freak him out plan just make sure that you won't get in big trouble with your parents about it

It depends on what he's takeing. I suggest setting him up. Catch him red-handed and confront him. Threaten to take it to your parents and all that good stuff. I think that would help.

so... let me get this straight... violence was the answer?

i would've set out blueprints of his room... with small things drawn in to look like you set traps throughout it... he'd spend hours lookig for all of them before he got wise...