A little advice please

Having rented my house out through the above agent in February of this year, I was informed in the July that my house had been raided and turned into a cannabis cultivation factory.

I was away out of the country so could not do nothing to check on the house, although the agent said he had been around and all was fine.

It seems the house was raided on the 8th April yet the Agent only notified my family of the event in July when I enquired as to the rent having not been paid.

The rent was 2 months late and I threatened legal action and the agent lied telling me he had found then growing that month.
When I enquired as to where the deposit was he replied that he had paid that to me as the 3rd months rent.

The tenants have totally ruined the house having removed all hand made cupboards, knocked holes in the chimneybreasts and drilled holes for large cables throughout the house.
Further to this ceiling have been damaged and furniture thrown into the garden, walls and plaster off and damp from the growing have damaged everything not to mention the theft of everything of value left in a locked room in the house.
The house is a Victorian builds building and in the last 30 years I have renovated it back to its original Victorian style.
The doors were removed plus door handles and used as light shields and nailed to the walls.
When the police raided the house they found 2 Vietnamese running the show arrested them and they have been charged and sentenced.
But the two gentle men that rented the house are of no interest to the police.
I have a copy of their passport and bank account and all details about them but the police have no interest in them. Saying to me that “how did I know they did not sub let”.
Well in the contract they are responsible for any damage to the house and are not allowed to sub let. Sub let the Vietnamese could not speak English hoe could they have installed, as the police say such a sophisticated setup”
I have a house in ruins, I am disabled and am not able to fix the house or have the funds to do so. I live in a building site.

The agent who clearly lied and covered up the crime and the police are not willing to apprehend the tenants who rented the house and engaged the Vietnamese to do the growing.

What part the agent had I do not know but he certainly covered the crime up for 3 months.
It seems we have the perfect crime, as the police are not interested in the Tenants who committed numerous crimes.
Permitting the cultivation of the premises with intent to supply
Criminal damage to the property
Theft.

Please some advice on this matter and how I can deal with it.