We had a similar situation when we rented our house out first. Total nightmare.
The rent was ALWAYS late, often weeks late. The tenant had no personal interest in the house as it wasn't costing him anything. We let to him and 2 others but we found out later that there were usually 8-10 of them. To cut a long story short, we ended up serving notice of eviction and legally evicting the tenant - and when they moved out, several thousands of euro worth of stuff disappeared from the house. Cue a long process to try and get it back.
If the tenant isn't paying you, I would worry about how they can be held legally responsible.