The outside of the Deer may be cool, the inside not so much. The bacteria inside, in the guts and other places keeps right on reproducing and makes it's own heat.

The guy that taught me said to find your Deer as soon as possible. Many nights I've spent hours looking for a Deer or Hog, often until 3-4 A.M., caught a couple of hours of sleep and been out again at first light.

The guy that taught me, said recover your Deer as soon as possible. Then prop the body cavity open with a stick, to cool the insides down as quick as possible. Once you get the insides cooled down and unless it is really hot out, you then have some time for transport or whatever.

I like to have them in my cool room (refrigerated closet) within four hours if possible, best scenario. Or in the cooler before the heat of day.

My guess is you may have had a perfect storm, the bacteria started building heat faster than your Deer could cool down.

No law against selling Deer here, prime meat can bring $7-8 a pound with the bones, un butchered.