Hi,
I need a mod to remove the stolen status from items. I mean, it could also not remove the hand sign, but I wish that the merchants didn't magically know which stuff was stolen and which stuff wasn't.

This would only be a temporary, off-label, non-immersive fix, but you can use the Remove Extra Data mod found http://www.nexusmods.com/oblivion/mods/46187/?. Basically, just drop all your stolen items into a container, and fire the spell at the container. When you get your stuff back out, the stolen flag will be cleared.

Hopefully someone will know of a more elegant solution for you, though. I always thought it was a weird thing, myself.