<human>: So, I live in a 4 bedroom apartment just off campus. It's one of those individual leasing communities. I've lived with one other person since February with no real problems. There was a guy living next to me that was moving out and was supposed to find someone to take over his lease.

About 2 weeks ago, him and the roommate approached me and said that he had found someone to take over his lease. Unfortunately, it was a guy, which I requested I didn't want to live with another guy, and they said he was just gonna stay in the bedroom next to my roommate's. When I first met him, I asked him if he had already signed the lease and everything, and he said he had. 

Then there were issues with the air conditioner. I noticed someone unplugging it, and when I plugged it back in, it was fine. Then someone was going in and turning off the breaker. I asked them both to stop, but so far, they haven't.

Today I went to management to talk to them about the issue and when I mentioned the guy, they told me they had no idea anyone had moved in. When I told them what I was told, they said that nobody had taken over the previous tenant's lease, and that guy should not be living there.

So now I have some random guy living in my apartment who has not submitted to a background check and I am more than uncomfortable. What are my rights in this situation? Should I confront him? My office management said they were going to contact the previous tenant to see what was going on but I want to get things expedited as quickly as possible. Is there anything I can do?

Condense the text into a few key points
<bot>: Someone is staying in my 4-bedroom individual-lease apartment and hasn't signed a lease for 2 weeks. What can I do?