It cames from the same source than anyone else seem to be getting it from - those randomly published notes from Dan James that showed up years ago in facebook group that was and still is under strict control of members of same family that controls the publicity of this case from the very beginning (and that may or may not be meaningful).
Lot's of drama there, lots of family members and people who knew girls there, possibly even those who knew what happened to them also there.
On top of that it wasn't presented in a form of "hi people, those are my findings", more like "hi, look at this and start commenting, let's see what comes up".
IMO those could be even made up in order to get some reactions. Same as with Shawna allegedly claiming showing up to pick up her son and chatting with the girls in house at Minot.