Lost/Stolen Cash Rent

[John Henderson]

Owner Occupied Building with Single Tenant
NJ

My tenant and I have a shared entrance where my door abuts his, with a third door to the outside that he's responsible for keeping locked.  I've been having tenants slide the rent under my door for 30 years without any problems.  This latest tenant begged to pay in cash, and, since the outer door is locked, and the money should be going under my door, I said okay.  I know, bad idea.

I've been checking the floor by the door every day since the first, and, yesterday, I asked him where the rent was. He said that he wedged the envelope in the door on the 3rd and that it had been removed on the morning of the 4th.  To date, he's seemed like a conscientious tenant, and appears to have a good job, so it doesn't feel like he's trying to scam me, but, at the same time, public access, as I said, is through a locked door, in the back of house with motion activated lighting in a neighborhood (with nosy neighbors) that hasn't seen a crime committed in decades.

What should I do?  Do I need to notify the police and, if I do, does contacting the police make me liable for the loss? Should I have my tenant contact the police?

If this goes to court, which I really don't want it to do, it boils down to my word against his, which puts me at an advantage, correct?  Instructions on how to pay are not in the lease, I only instructed him via email.