Tenant selling drugs..........?

I am closing on a house that is occupied by tenants on a month to month agreement with their current landlord. When we close I plan to give them 30 days to move. But can this notice to vacate be expedited since the tenants are selling drugs. They have not been busted but I live only a few blocks away and know that they are selling. What can I do to get them out sooner after I close. By the way, the current landlord was not ask to give notice in the purchase agreement, and therefore, did not. What legal rights do I have? I live in Illinois.