In my opinion, the truly crucial aspect of the Peru case is the highly unusual gap between the alleged time of Stephany's death (early Sunday morning) and her body being found (Wednesday morning). If Joran killed her, the length of time until the body was discovered makes little sense, and imho the explanations offered up ("I'll be back in a few days," "don't bother my girl," etc.) are lame and counter to most everyone's life experiences.
Now, I fully acknowledge that any conspiracy theory has the same problem- how do we explain the gap? Surely, any conspirators would have been smart enough to have the body discovered shortly after Joran left, right? Well, not if this scenario, or something like it happened:
Let's say that Stephany was supposed to be the "bait" to lure Joran into whatever sting was planned for him. What if she felt sorry for him, after meeting him, and backed out? What if she told him everything, and urged him to get out of there quickly? Maybe she gave him her keys and let him take her car- telling him where to leave it (this would give him a head start and take her car away from the hotel, making it less likely they'd think she was staying there). She would have been terribly frightened then- did she just stay in his room for a few days? Maybe she snuck out? Who knows- the point is, under some kind of scenario like that, the later discovery of her body (this would end, of course, with her being killed for betraying them) would make sense. In my view, it's the only theory that explains that nagging three day gap.
Is this far out? Sure, most conspiracy theories are. But then, most conspiracies are far out, too. Okay, ready for comments.