@Lindsey Spivey  Take this post as it is...coming from a neurotic psychopath who doesn't trust anyone. 

Any psychopath that is willing to come reenter a unit they no longer live in - risking getting shot or going to jail for burglary in the process - does not give a damn about a key.

One spends his nights trying to wrestle down drugged out AIDS infected psychopaths trying to kill him for nothing but doing a blue collar job and wonder if he's going to be sued tomorrow.

It concerns me that you are defending this psychopath quite a bit!

You're hiring a new property manager to manage your property, not run your business.I can't see why you'd need to change the locks, unless you suspect that your current PM is a crook or a psychopath.

I had to learn the hard way that independence, freedom, from the army of corporate psychopaths out there obsessed with tormenting workers, had to come by way of FINANCIAL freedom, not just food independence.And that realization only hit me about two years ago. 

It would have been messed up if any one of us would have died all because that stupid white dude was scared of a black crackhead.And the above scenario is what I believe to be a far more representative scenario of common gun use in public – rather than we become heroes and shoot deranged psychopaths.

Then again I’ve been in sales most of my life so I’m entertained by swimming with sharks. ya learn how a Psychopath works I get it  LOL..

How do you know you have not rented to a undiagnosed psychopath.  

If you're in RE long enough you're going to be sued at some point, but it would take a psychopath of a seller to do so in this case given the facts you've presented.