I'm late coming on the thread and didnt take the time to read every reply but I did read some...at this late point not sure if op ever actually found out who did it
I know I'm really new here but I will add in my two cents also...I guess we all base our advice partly in our own beliefs and leanings...
I have always felt a strong conviction to not take things at face value, things aren't always as they might seem to us
I guess I am of the camp who feel nobody really knows who did it. The op admittedly says she can't in any fairness say for sure who did it, but then goes on to say the nephew found the dog food in the cheesecake, as if that means he's guilty. I understand the point but one could actually say the opposite....if he was the one who did it, he probably wouldn't want to make himself stand out that way by findng it. If I put dog food in cheesecake, I wouldn't want to make it obvious by drawing attention to myself in that way. I might pretend to be asleep in bed instead,..so one can't say either way. Yea, it could look guilty that he found the dog food, but if you take it another step, a guilty person on the other hand might not want to look obvious that way.