I operate on the principle that if there's no lock on a unit, anybody has access to the contents, so anyone could be guilty if something goes missing. If it's my lock, and I exclusively hold the keys to a tenant's unit, I'm the only one with access to the contents and the only one that could be accused of "mysterious disappearances".
Having said that, there is a wide legal gulf between being in a position to be accused of the possibility of having taken something from a unit and of there being evidence sufficient for a DA (or Crown Prosecutor, in Canada) to lay a theft charge, and of a court to find for a conviction.
In theory, before anyone can be accused of a crime, there needs to be some evidence that there was, in fact, a crime committed. Is (are) the "missing" item(s) on an inventory list that the tenant made of the contents? Was (were) the "missing" item(s) found at a flea market, hock shop or on eBay and could it (they) be positively linked back to you? Are you wearing the guy’s sweater (as has been reported to have happened)?
Not likely, if you're not a thief who happened to acquire his dream job. And, if that is the case, there's likely going to be more than one complaint about the facility.
Then, of course, there's the
PR aspect. How likely is it that the tenant will have sufficient credibiltiy to badmouth you with impunity?
This one doesnt have a clear-cut, right or wrong answer. But I can say that mailing keys by Canada Post is prohibited (for some reason, presumably); USPS may not have that regulation.
Bill