Have we researched the date she went missing? Like, what was going on in town that night? What did she do on her date? Where did she go? What movies were playing, what restaurants were open? What time did clubs close?
What do we know about Heather? Was she still attending college? If so, what is her major? What kind of grades does she get? Does she have any kind of depression issues? Is Aheather outgoing? Funny? Does she have alot of friends? What do her friends & family think about what happened to her? Do they feel its somebody she knows that's responsible or do they feel she was targeted by a stranger? What kind of guy attracts Heather? Could she have been lured by somebody that needed help? Could somebody have won her attention with a good smile? Or is it possible somebody knew she wasn't home and waited there for her to come back so she could be kidnapped? Way would be the reason to park her car at the landing?
Imo, if shes not responsible for her own disappearance, then I don't think she's the one that parked her car there. If so, why would she leave her stuff in her car? Doesn't make sense.