He gets a monthly salary from the government as he was an early retired civil servant due to injury.
He has been ignoring my messages and all attempts to contact him.
I haven't been requested to fix anything in the 1 year that I have rented to him, as the flat is brand new.
People finding the deceased's body, days, weeks and even months after their deaths are not unheard of. Usually the deceased are been lonely people living by themselves. Their spouse may have passed away before they did or they were divorced and did not remarry. They may also have no close family member (or lost contact for whatever reason, estrangement, etc), their friends and relatives have either died or lost contact. So when they go, there isn't anyone aware of their passing.
My understanding is that if you give one month's notice he has to leave. ( what my tenant did)
Since your civil servant tenant has to leave, you will need to rent it out.
So you need an agent. You can ask an agent what is the situation by showing him a copy of the tenancy agreement and see what he says, and ask him to show you his company's standard clause to see if it better protects you. It's free advice.