If he was headed to Philadelphia on the 29th, I'd say his ultimate destination was Mitre (who has let out absolutely no info) or a Sporting event.
I'm sure he has a place to stay in that area if not at Mitre itself.
They said he didn't return any emails to his buddies on the 29th.
Nevertheless, it looks like they have now traced actual calls that he made with all the attached info.
TIME and LOCATION is everything.