Mail tampering

IANAL, but I suspect/hope I might have legal redress for this situation.

Recently a friend sent me a package. However, she had it mailed to a previous address, about a month out-of-date. So Saturday evening I get a call from my old landlord, and he says that the current tenants had received it and put it outside on the curb of the road. This was bad, since it’s not the best of neighborhoods.

I immediately bike over to the apartment, but of course it’s gone by then.

Does this count as mail tampering or theft on the part of the current tenants? Does the landlord share in any legal responsibility? Is this a criminal or civil matter?

I’m unsure if it was UPS/Fedex/USPS who did the delivery, if that matters.

Not a lawyer here either, but AFAIK it’s only mail tampering (a federal crime) if it was sent via the U.S. Mail. If it came by a private courier like Fedex it would be a civil matter, and the liability would probably lie with that company. You might make a case against the tenants for theft, but that seems like a stretch. I can’t see how the landlord could bear any responsibility.