I have a son who is 27 months old. There is no way he could be left in the car. He can scream very loud.
Only if your baby is awake. By the time a sleeping baby has been subjected to smothering heat, he might not even wake up.
“Harris left Cooper strapped in the back seat seat of his vehicle for nearly seven hours as the weather reached the high 80s.”
I don’t think that forgetting his son in that fashion is remotely possible. If he actually did, it is negligent homicide.