It is not disclosed in the question whether or not you are alleging that a theft occurred. If at any time during its shipping process it crossed state lines it could possibly fall under the federal law,"Theft From an Interstate Shipment."
HOWEVER, the problem is that the incident occurred AFTER the shipment was delivered, not DURING shipment.
IF you are alleging that the tenant committed a theft, you would have to contact your local law enforcement agency to report it. Simply opening a box (by mistake?) is not in and of itself an unlawful act.
You could lodge a complaint with FedEx if they accepted the tenant's signature instread of yours.
to what ends
congress
City, governs cities and villages, State, governs states and Federal governs the country.
hippa
The Judicial Code governs federal courts.
Banks and loan companies. The federal government has laws.
FARS Federal aquisition regulation
Fiscal Law
Fiscal Law
There is OSHA - Occupational Safety & Health Administration which governs the working conditions for any commercial place. It is a federal agency under the department of labor.
The Federal Election Commission (FEC) governs the financing of federal elections and keeps track of contributions.
It is a US federal law/statute that governs warranties on consumer products.