My question involves landlord-tenant law in the State of: Missouri

A tenant who had been living with my 2 sons (all paying utilities, as agreed), for over 2 years, opted to stay when my sons moved out. He brought in 2 other house mates. All payed rent on time and lived there for 4 months. At the time they moved out, I discovered that they never changed over the utilities (water, gas, elec.) to their name. The electric and gas automatically reverted to my (the landlord) name. The continuing tenant had been the liason , collecting rent from the others and paying, etc. and assured me "he" would pay the back utilities. He is now avoiding me.

They never had a rental agreement (even when he did pay utilities for the 2 years prior). Do I have a case?