According to investigators she injected herself with a massive dose of a fast acting drug then threw the injector away, did something with her shoes (no explanation as to what, she was barefoot and her feet were clean so must have been wearing some if she walked there herself and her shoes were not found at the scene), and then tied herself up in a painful and awkward position in the seconds it would take for the drug to affect her movements and render her unconscious.
Those investigators were working hard to deny that she had been being stalked for years while they had blamed and accused her. They didn't even notice when they passed the point of incredulity.