Undocumented roommate / funny business?

[Jessica Monroe]

We recently purchased a duplex and tenant in unit 1 is good about keeping me in the loop about what is going on. Within the last week she let me know about a "new roommate" in unit #2. A few days later she lets me know there are a lot of people coming in and out of unit #2 at all hours and neighbor noticed a lot of traffic. She said she is scared because some people have been coming to her door looking for someone. 

My question is what is my landlord responsibility. Most importantly we don't want my tenants to feel unsafe, #2 if there is any funny business going on we want to put a stop to it quickly. However, with nothing "on record" where do we start? 

I did tell tenant #1 not to be afraid to call the police immediately if something gets out of hand but she doesn't want to cause any problems. 

Thank you in advance for all your input!

[Joe Bertolino]

I have a client that buys and turns around challenging properties, Mostly 4 plexus and small apartment complexes. He puts up cameras and has an on-site meeting with local law enforcement for a “security walk through”. The drug dealers and hookers typically move out within 30 days. Their clients don’t like being filmed. Plan on a few cameras being damaged