Stupid Roommates

So, we've had stupid roommates.  But none of them have stolen stuff.  Until now.  The floor of my house is a bit sketch right, so for the past few years, I've had a pair of sandles that I wear outside my room.  Now, one day they go missing.  I figure I just put em under something - I lose stuff often.  A couple weeks later (after I tear up my room twice looking), I find 'em.  On my roommate's feet.  Wtf?  Ok, so I ask him where he found them (they were just laying about, so he took them) and got them back.

Great, yes?  Just a misunderstanding?  No.  A week later, I leave my sandles by my shoes when I leave for class.  When I come back, they're gone.  I see them in the guy's room through a crack in the door, but he's sleeping, so I can't really steal em back.  The next day, I have to fly home.  When I come back, he's gone.  Sandles too.  I realize this isn't a big deal, they were worn out sandles that I got for free.  I just hope nothing else is missing.