If you are standing/walking in the middle of a field at night, you are pretty noticeable. There is a horizon behind you and you are a shadow and the eye looks for movement for clues in the dark. Also, its quiet in the country at night and sounds carry very well. Your voice, or more to the point, a woman screaming, would carry quite a way and would be noticeable. It's easy to trip on things, and if you have a flashlight to prevent that, people can see you a long ways away. Most farmers have dogs, who will be alert to things that are not where they are supposed to be. Finally, it is very easy to get turned around in wide open areas with trees at the perimeter, especially if you are driving through that field with the car lights off so as not to be a car driving with lights on at night. There just isn't the kind of landmarks that you have during the day. Source -- me- used to do astronomy and would be in the middle of fields at night with a car, leaving with the lights off and walking around with no flashlight so as to not ruin other participants night vision. Even with a trail blazed for the astronomy group, cars would get lost, including me once.
(IIRC it's been raining in Charlottesville this past week. Not Good in regards to finding DNA evidence)
