I am in Paris now and I am very surprised if Justin would stop on his way to the airport. Where was his luggage, and do they know where he stayed while in Paris? Had he checked out of Paris lodgings? That would surprise me since there is so much to do here and I've not seen anything between Paris & CDG to explore. Not with all in Paris so I am again surprised he would stop there.

Is there any chance he met someone - came with them out of Paris and then was robbed on his way back into town? You are right this is just a gritty suburb and it would be very surprising someone here to see Paris, would go out there unless he was escorting someone home or was invited to someone's house. This may have happened and they never heard from him again, thinking that he had moved on.

Also from the train from Paris to CDG, there is nothing attractive to stop for - especially with luggage. Most folks on way to airport are on a mission to get there not to stop on way. This is not charming quaint area for folks on way to airport to stop. Think New York city and Newark airport.

Very sorry - I suspect robbery gone bad.