Deer season is cranking up, so I think if she has been placed in a rural area, she will likely be found, unless a great deal of effort went into hiding her. For a while, that scent of death will be near her, I'm sad to say, if she was killed, and will only attract attention.
Also, a second year college student is no child, if not in college, she could be married, a mother, holding down a full-time job. They have to assume responsibility for themselves. If they are naive, the parents should have had a long talk with them, before leaving home, about what can happen, what HAS happened at the very school she is going to. I'm not blaming the victim, but I'm also not blaming her friends. This age group can be very stubburn, 'don't tell me what to do, I'm doing what I want to'. In fact, they seem to make more mistakes than a 13 yr old. I'm speaking as a mother here, been there, done that. She could have just as easily been leaving the library, to return to her dorm and this happen.
Hopefully, this will make other students, parents, school officials think, how easy it is for something to happen. If you're alone, if you're intoxicated, if you are not paying attention. Once it does, its too late.
This is all MOO, and I'm hurting for Hannah and her family, and praying for a resolution.