All the evidence is not in.
There is sufficient evidence to fulfill the requirements for charging him. They cannot charge him without all the evidence needed for this; the process that follows is another matter entirely. Evidence can still be introduced during trial, but all the evidential requirements to move the process forward have been fulfilled.
There is a lot of speculation about what lab results have been returned and assertions about how it can only mean ONE thing. So far we haven't heard anything about a sexual crime being committed; this might come later. There are many different things for which they could have tested, not just semen.
Again, my mind goes to the way a law enforcement officer stated unequivocally that DB was guilty and how this can affect finding a jury pool that isn't prejudiced.
And, please, before you jump on me and say that I'm saying he's not guilty, all I am saying is that there are mistakes made on the fringes of an investigation that can damage the process of going to trial and getting a conviction. There are those sitting in jail who shouldn't be because of overzealousness and mishandling of evidence, and there are those who SHOULD BE in jail who have managed to go on with their lives for similar reasons.
DB might (again...innocent until proven guilty, not my personal invention but legal protection for us all) be guilty, but there are many factors at play here. There IS a difference between crimes committed due to mental illness and crimes committed out of pure evil. We don't know the whole story of how and why this came to pass, and we need to wait patiently for the investigation to continue so that a proper case, that can be fairly and clearly prosecuted, is prepared.
What happened to Cash Gernon is unforgivable, mental illness or no, but we can't immediately start adding conclusions on top of speculation.