Where was the crime scene?

In one sense, the whole house was the crime scene, but was she killed in the wine cellar? It seems like the police never really established what room she was killed in. So her body was the only real crime scene. But there had to be more. Was she restrained? Did she go with her predator willingly? She was apparently still alive when she was strangled- but where was that?

In most crimes you hear about a site where the murder happened, and a secondary site where the body was hidden or dumped. In this case its all muddled. There would have been evidence at the site where she was actually killed... and there was a murder weapon. Why don't we know where she was killed or what she was hit over the head with?