As some have also mentioned, it is strange that Casey doesn't ask any questions about the mystery man, and, George offers nothing up aside from inviting him in to eat with them.
The reason Casey doesn't ask any questions, IMO, is cause she already knew about it.
Letter's were already being secretly passed between them, or, Baez told her about it.
Otherwise, she would have been a nervous nilly wanting to everything about who he was, what he wanted and what was said - and not because he may have been the evil kidnapper either.
And, as far as the Anthony's "inviting" anyone into their home out of the goodness of their hearts = they can sell that to someone else also IMO.
These people that took hammers and hoses after anyone that dared to cross their crime scene tape, inviting a stranger into their home??
A stranger, when Casey had them believing that everyone's life's were in possible danger, and that was why she couldn't talk.
A stranger, when the Anthony's have never trusted anyone before in their entire life's??
Nope, not biting on that one - didn't then, and certainly am not now either for that matter.
As far as it being Mark Hawkin's, not sure.
If it was, then, I would think that they would have been really suspious of him returning in October again, so soon, esp with him being military.
If it were me, and it was Mark Hawkin's on Caylee's birthday, I would be wondering what and why he is back again in October.
And, I would be on my guard, really, really on my guard around him ~