Well...how about this? It has been reported in various media outlets that when he was arrested he allegedly asked if others had been arrested as well.
It is also known he had an interest in what a criminal's indset is before, during and after a crime. Such was the nature of his online survey/research study and request that criminals reach out to him about. And one of his neighbors indicated BK had an interest in how criminals think.
Plus his defender in PA stated that BK believes he will be exonerated.
Plus the affidavit was written prior to his apartment/car/parents house being searched. We don't yet know what, if any, incriminating DNA was found in those locations.
I wonder...perhaps HE did not commit the murders. Perhaps it is even sicker than that. Perhaps he was "studying" the actual murderer - maybe a criminal who responded to one of his queries. Perhaps he accompanied the criminal on various stalking trips to the victims' house. Perhaps the criminal was inside the house earlier than the timeframe described in the affidavit. Perhaps BK helped drive the murderer away on the premise that DNA at the murder scene wouldn't be tied to him - not realizing it was on the sheath which he assumed wouldn't have been left there. Or maybe the murderer left the scene separately and BK was there just to observe from afar - and returned the next day for the same reason.
Perhaps that is why he supposedly thinks he will be exonerated and why he asked if he was the only one arrested. If that were the case he WOULD be exonerated - from the murders themselves. But he would still spend the rest of his life behind bars.
Of course I have zero proof or confidence any of this is correct. It is something I just made up. But it is one way I can think of that could explain how his dna could have been on the sheath without having been in the house and still explain the cell phone data and his car being captured on video in corresponding locations
If something like that were true, he would be just as sick in the head - perhaps even more so - than if he did the killings himself. His fascination for criminals' mindsets and "studying" a murderer in real time would be a way to vicariously live out a fantasy he might be too afraid to carry out on his own - and perhaps justify it to himself in a sicko sort of way as he was doing it in the name of science. He doesn't kill people - he just "studies" those who do.
If they end up not finding any DNA from the victims in his car or apartment - then maybe such a line of thought would be worth looking into. My guess is they have much more solid evidence on him than has been made known and they probably found even more in his car and apartment