I will return to this situation in the end of this post, but first let me show you why the age of a person can be tricky when it comes to the IRS.

What a tremendous accomplishment at such a young age. 

Learn the eviction procedure for your area, perhaps contact a lawyer in the field to help you with this one, and get the fraudster you're currently housing out on the sidewalk to sleep in a cardboard box where they belong.You're going to lose plenty of money here, but this will never happen to you again, and you can minimize your losses if you move as quickly as possible.

Quote from @Brandon Larson: It's important to have established policies and procedures, but I wouldn't put a lot of effort into that with only a duplex under management.

The standard legal procedure, as far as I understand in NC is the landlord must make reasonable effort to re-rent the property (which I will), and any vacant time till new tenants are found must be paid by previous tenants.

The rules and payment standards vary significantly from one area to another, so familiarizing yourself with the local housing authority's procedures is key.

That means having procedure and protocol for every situation--or at least, every common situation. 

The PM should be an expert on state law, and they should have policies and procedures in place to handle these situations.

What they said.....everyone over the age of 18 has to have a background/credit/ ID verification and sign the lease.

You should consult a real estate attorney or tax advisor to handle the legal and procedural details.From a tax perspective, there are several implications.