JMO.
I have followed this case from the beginning. I hesitate to post here, as I only heard it once the day after the girls were found and it was local media, but I do not have link, nor can I verify the source. I do not nor have I ever had FB or any social media for that matter, so my only source would be news, either televised or read in a paper. In the very beginning there was reference to something at the scene that leaves no other option than it to have been a sexually motivated crime.
I have seen it referenced here a couple of times over the years, and I'll leave it at that. I don't think KAK or TK are BG. I don't think, BG is any of the known POI's either. I do believe KAG was sharing information with similar types, and thus, even the A_Shots acct. I'm not so sure he was the business man some would believe, but rather just sick and trading and gathering material, with likeminded persons. For this reason, I believe KAK is linked to the crime, along with the A_Shots account. I am not sure he knew the perp in the real world. Possibly only online. This crime, what little we know about it, leads one in one sense to lean, to a personal connection as staging often suggest, hands folded, etc. where as the other was much more severe yet less or differently posed. A familiarity can be formed in short order, even by stalking. When they say a familiarity, it is directional. The victim does not necessarily know the perp, but the perp knows the victim. Sometimes from a far. So, more of an opportunistic act. My opinion is this is because he was not expecting one of the girls to be there and so his personal connection was acted out towards one and the other was collateral damage. The Marathon could have simply been a marker for directions for the perp. I try to steer clear of what I can not verify, but the one thing from the beginning has stuck with me. I have tried desperately to find it in the latter years, but could not. I think, because of the grotesque nature of the act, it quit simply was asked of whom ever reported on it to simply not reference it again. Also it would be one of those things LE will use to verify the killer if ever there is a confession.