Need advice on non-compliance with rules and regulations

I would like to know what could be used as defence when charged with not following an establishment's regulations. See, I accepted an item from another person when security regulations say that valuables and other personal belongings should be kept by owners in their own appointed places, and that any items found on a person that is not needed in the workplace (such as the item I accepted) should be confiscated and turned over to the immediate department head. The problem here is that the item was stolen.

What could be said to defend against a charge of the unacceptability of tolerating the other person's bringing a valuable item to the workplace, and my non-compliance with the rules and regulations of the establishment?

^ I hope that wasn't too confusing... Thanks.

confusing