Can I evict someone who is not on the lease?

[Neil Whitney]

I have a tenant who let her boyfriend move into her apartment sometime in the last year. I suspected that he had moved in so we sent a notice to the tenant who is on the lease about adding her boyfriend to her lease and that we would have to perform background check like we did with her when she moved in.

She called us today and ...

Here is the tricky part, she does not want to add him to the lease, she does not want him there at all. She has called the police to have him removed but they said they can't do anything it's a civil matter. I am thinking I will go over there and tell him he has to go and hopefully that will be the end of it. I will charge her to change the locks so he has no access. Now if he refuses to leave can I evict him since he is not on the lease at all? I know I could evict her but I dont want to lose her as she is sweet and always pays on time, she has been with me for 18 mos or so. This is one I have not encountered or heard of how to handle. I know the answer is likely in the room. Thanks for the help in advance.