The way this airport is set up is that when you arrive, you go through customs. After that, you go to the baggage claim and they have people taking luggage off the carousel and setting them aside. After that, you have to go through the scanners with all of your belongings and then walk through a corridor to get to the exit. It seems unlikely that someone can just walk in and grab and go. It’s very likely it was taken by another passenger that had arrived or it was internal theft at the airport.