Well they do havve him and her at the science fair early Friday morning in photos? So he was at the school before school started.
Right, and there is a very narrow window (perhaps a minute or two) where she can say that she left him there, but she could have taken him to the car and left. If no one noticed in them together in those couple of minutes, she would have created an alibi. If she was looking to create an alibi, she would have been very careful to not let anyone see her.
I do not think this is the case!!!! But I do think it is possible.