This study also doesn't consider how easy it is to frame the usual suspect. If you want to kill someone's wife all you have to do is frame the husband. Law enforcement will ignore every other lead if they are led on a cookie crumb trail that points to the most probable outcome.

Seriously though, is it really that hard to plant finger prints and DNA at the scene of the crime? What about law enforcement planting evidence because they are "sure" the person did it?

The judicial system is a sham. We are much more focused on revenge and pointing the blame rather than true justice and making the world a better place.