Possible Smoking in Unit

[Bradford Myatt]

Hey All, I've approached a potential problem and I was hoping for some feedback from anyone who has been there before. I recently purchased a MFH and inherited a first floor tenant. I purchased the property from an owner who managed the property from afar and didn't have much oversight as to the property. My realtor informed me that the downstairs tenant, whom I inherited, had a history of smoking in the unit. I clearly pointed out in the lease and affirmed to the tenant that smoking is not allowed. A new upstairs tenant moved in and has been complaining that she smells smoke from the downstairs tenant. When I ask the downstairs tenant she denies smoking in the unit, and claims it might be her candles we are smelling. What course of action do I have? I have already verbally and in writing reminded the tenants of the smoking policy. Any ideas?