Let's play devil's advocate for a moment...
There have been lots of people gaining internet celebrity from this case by creating social media groups with thousands of members, making YT videos with thousands of views, blogging, etc. Ordinary folks who have no ties to the case but have come out of the woodwork and made names for themselves by discussing it and setting themselves up as "experts" in it. Some are good, some are great, some are not. Most we are not allowed to discuss here, and for good reason.
What IF the "witness" to BG wasn't an actual witness at all? Since we don't know the circumstances or the details of what they saw, and the details haven't been discussed in MSM, we have nothing to go on but what LE tells us. And what we were told today is totally different from what we've been told in the past.
I'm not a conspiracy theorist and I pretty much take what LE says as fact until I know, for a fact, that it's not true. Their words today are inconsistent with what they've said in the past. It makes me wonder. False confessions from people who had nothing to do with the case DO happen. I am sure false witnesses occasionally come forward as well.