Same diff if all they have to do to is say they are

Either way, this person is incredibly ballsy and an absolute genius, especially if they just leave with the money and don't actually take anyone (to avoid kidnapping charges).

All you gotta do is go to your van to "get an evidence bag" or "handcuffs", then start the engine and drive off. By the time they realize that you're never coming back for the zip tied person, you're already hid the van and swapped outfits several miles away from the crime scene.