Landlord responsible for tenant behavior!

If a landlord knows his tenant is causing problems for a home owner next door, and deliberately does damage via vandalism in excess of $10,000.00 damage to the home owner’s home and vehicle, was arrested and goes to trial on 9/30/15, is the LANDLORD responsible, along with his tenants, IF he has been contacted many times BY the home owner about the conduct of his tenants, requesting he get his tenants in line, OR has requested his tenants harass this same home owner to aid and abet HIM with directing storm water flow onto the home owners property deliberately causing additional damage to their back yard area. Since the landlord took NO action to evict these tenants is he not as culpable before and AFTER the fact when this criminal felony was perpetrated upon the home owner by this landlords tenants? This is fact, and in the State of Illinois. Help!!