Returning a Stolen Item

"He shall return that which he stole"Leviticus 5:23.

It is a mitzvah for a thief to return stolen property to its owner. (If the thief denied his crime and falsely swears as to his innocence, he is required to repay the principal plus 25%.)

The obligation to return the actual stolen item only applies if the object has not been substantially altered. If it has, then the thief must make restitution by giving the owner the monetary value of the stolen object.