Possible ways she ended up there and no one told LE:
1) She met up with some one when first arriving in Charlottesville, and went to a party in that area she was found prior to the concert, and stayed there, or went to a party after being stuck outside JPJ. They partied and she, in an under the influence state wandered off. At a big party who would notice one girl had left? Person that took her there is either a bg and doesnt want to say anything or is too under the influence to realize Morgan is the girl he brought/or thinks the girl he brought left with some one else.
2) She met up with some one when first arriving in Charlottesville, and went to a party in that area she was found prior to the concert, and stayed there or went to a party after being stuck outside JPJ. She partied there until some one at the party tried to take advantage of her (whether she was or was not under the influence is immaterial here, she is a victim either way) she flees the party and gets lost. Person that brought her there is definately a bg and doesnt want to be known.
In either of these cases, the way she was dressed, and the weather that night, it would not take long of hypothermia to set in.
3) She met up with some one when first arriving in Charlottesville, and went to a party in that area she was found prior to the concert, and stayed there or went to a party after being stuck outside JPJ. She partied there and went for a walk with fellow partiers who were so under the influence they didnt realize she was no longer walking with them. Person that took her there doesnt realize she is gone.
4) She met up with some one when first arriving in Charlottesville, and was on her way to to a party in that area she was found prior to the concert, and stayed there or went to a party after being stuck outside JPJ. While on the way to the party, some one with her noticed cows in a pasture, and decided, in an under the influence state, to pull over, climb a fence and go cow tipping. Once across the fence she wandered off, and they looked for her but coulnt find her, and went on to their party. Again, people she was with are partying, dont realize a girl they just met isnt there anymore. By the time they realize it was Morgan, they are afraid to come forward.