As a result of this horrific case - there have probably been thousands of people searching this topic.
I wondered if the stupid couple tried to skip on daycare costs and considered leaving the child in the car for a few hours here and there. What is so compelling is the fact that the daycare was in the same building as the father’s job. (Home Depot). And why did he check his car at lunchtime? Was it to see whether the child was dead or alive? Poor little boy - we may never know the truth.
That sounds like a very plausible explanation. It leads me to wonder if the parents left their little boy in the car at other times, and when he seemed to be OK, they believed they could get away with doing that more often. (?)