Well, I dont know how it works for this kind of thing, but if the leg had been found in an archeological dig it would have belonged to the site owner - so I say give it to the owners of the mini storage and let them sort it out.
He left it there thinking that he could pick it up whenever he wanted. According to the article the storage company repossessed it along with other items as payment of outstanding debts. As far as I can tell the legal issue ought to be between the legs original owner and the storage facility. If the storage facility was within it\'s rights to repossess it then he really doesn\'t have a leg to stand on and it\'s nothing to do with the new owner.