As you may know we live in the Upper Peninsula of Michigan which would definitely be a "cooler midwest state". Last week my neighbor called me at work at 10am that a buck had been hit and was laying in his yard. The deer had been hit around midnight (temps in the high 30's - low 40's). I got out of work at noon and went to check it (temp near 50), it was already bloated and I definitely didn't want it. That was after only twelve hours, after 2 -3 days I  wouldn't touch it.
    The biggest giveaway would be the smell when they gutted it.

    Dave