Dead animal in the UP – Stinkt verwesten – what can I do

Hello, I have any dead animal in the rear area – trunk! Have already searched everything, under the car – in the engine – etc. Have made engine wash, and the complete car with the steam radiator processed. The smell comes from the trunk. Can it be that there may have been a mouse lost in the retro-reflectors. How do I get there? Will drive on Saturday on vacation, but I think that is not so nice with the stench. For helpful tips and tie up I would be very grateful. Greetings Markus[b][/b]