Close examination reveals that the lock was less broken on the door than partially removed. With another pin or two, it could go back into working order without any effort at all. It's difficult to tell when it happened, but there are human fingerprints around it.

If they examine, all the other exits except for the one from the lobby to the suite - to the kitchenette, to the hallway, to the window - either lack locks or have necessary pins to the lock removed.

The goo, upon smelling it, smells faintly like some sort of rot, perhaps even a corpse.