I too had this thought. His "what did I do" squarely puts the blame on him.
One thing I'm wondering. If he's faking, when he came out of work why not do the "big reveal" right there? Why drive away and stop at a new location?
There's a lot of reasons that "later" the cops would arrest him. Like them finding benadryl in the kids system. Or finding out he checked the back of the car. Or him searching the internet. Or cell phone records that reveal he ignored calls from the day care.
But they slapped the cuffs on him right then and there. So I'm thinking there must have been something he said or something in the child's body that just proved him wrong instantly.
There's also not been much evidence revealed by the police but they seem adamant he's guilty of murder.
So what would show up right on the spot. Rigor mortis and the condition of the body. And also maybe the body smelled of decay and they knew there would be no way he could have gotten in the car and not noticed it.
IMO, if he's faking the scenario and covering for himself/his wife (and therefore child was deceased prior to being put into vehicle/carseat but was staging it to appear the sad case of a Dad who accidentally forgot child in hot vehicle all day), his statement of "what have I done" means little. Him stating that doesn't change the fact that there could be a cover-up on his part...I'd fully expect him to say this, in keeping with the "OMG how did I forget my child in my vehicle all day!?!" ?act.
If this was all staged and child deceased prior, my guess is that he made the 'discovery' where he did vs parking lot at work so that he'd have witnesses as to his horrific discovery and being so shocked and distraught.
I find it odd that he reportedly got out of his vehicle, ran into fast food restaurant and screamed for someone to call 911. Why wouldn't he have his own cell phone to call?.......who doesn't carry a cell phone these days? To me, IMO, he did this all for dramatic effect. Again, just my opinion.
Also wondering.....if child wasn't dropped off at daycare as per usual, would it be usual practice for daycare to contact parents/legal guardians of such a child to find out if everything okay? And if so, would they not have called both him and his wife to inquire, you'd think much earlier in the day, such that the child's whereabouts would have been discovered much sooner?
Also, I'm assuming the wife must work...........otherwise if she was a stay at home Mom you'd think child wouldn't go to daycare, right?
Has it been confirmed that they had only one son or 2? I've heard Cooper and Connor, and that each went to a different daycare - which would be a little odd?
Would Dad not have noticed at least some kind of bad smell upon first entering the vehicle............to immediately cause him to realize child in backseat?.......due to the many hours of heat, possible beginning stages of decomp, etc?
Wonder if couple were having any marital issues.........talk of separating? divorcing? possible custody issues?