Rigor mortis lasts at the longest for 72 hours.
I don't think THIS is rigor.
Besides... how could you perform an autopsy on someone with rigor mortis?
I don't know the how, but I do know that there are cases where there is a sort of 'rush order' for an autopsy from LE, and it is done while rigor is in full effect - I've seen it noted in homocide autopsy reports fairly often.