I think they underestimated the Amish because of their lack of technology. I don't think they were expecting a witness, especially one who could speak English well enough to give a very good description. I also think they expected to have a lot more time to take care of things because there'd be no phone or car to use to contact the police, if they chose to. I wondered too if a friend was supposed to pick them up where they were dropped off; if not, why bother telling them to stay there? MOO