Hi! I think you made two very good points to at least consider. If the staining turns out to be her blood (I'm not sure we even know it is blood yet?), then, I agree, it doesn't make much sense that SC did something and THIS is potentially the only big clue left behind?
As far as him being set-up, I frankly had that thought go through my mind too. I think it's possible with the advancement in forensics, criminals are getting smarter. For one, if a suspect is handed to them on a silver platter and there is some evidence against that person, I believe that is then where most of the resources go. Resources are limited so, yes, I believe some of these types of decisions are often made and maybe with the help of the DA. You'd be surprised in some cases how much evidence is not tested or there is no advanced testing. Probably not true in this case though and I am not sure if someone specifically would have set up SC to take the fall (or how or why) just that this case does sometimes have that feel about it to me.
Most murderers make one or more mistakes. and I think that would be especially true if someone had never murdered before. ..MOO Serial killers are more careful,more crafty..MOO