dead mouse in vent

I have a 2002 SS monte. Evidentally a mouse has crawled into the duct work and died. I need to know the easiest way to gain access. I pull the cabin filer in hopes it was there but it isnt. The smell only comes out when on recirculated air. Am I going to have to remove the entire dash?

Check up in the blower motor area (Under the passenger side Footwell) see if its around there.