I wanted to add to what I have already said. This is my opinion and cannot be confirmed.
The police said they would have liked to have seen the glass before it was cleaned up. That has always intrigued me. If it were deliberately broken (with a metal baton?) that would have confirmed why it was broken. It was to more likely ensure that entry would be gained by the the first responders and subsequent visitors who would surely destroy forensic evidence. Again my opinion as no way to confirm that it was deliberately broken but it does speak to the probable reason why police would have liked to have seen the undisturbed glass shards.
As to the missing key it could have been used to gain entry if the perp had it on his person or it could have been used to leave through the side door. The van could have been backed up close to the back of Sherrill's car making it less likely to be seen when loading the women into the van, having taken them out of the side door and not the front door. There must have been some reason that key was missing from Suzie's effects. She never had one; it was taken from her for security reasons or the perp used it before or after entering the house.
Again, it is my opinion that someone who knew police procedure would know how to avoid leaving usable forensic evidence. If the house was locked, short of breaking down the door, the crime scene would have been left in pristine shape. That is why it was necessary to have visitors corrupt the crime scene. Again, this is my personal opinion and cannot be proven. But it makes the most sense to me over these many years.
