Sandra's daughter LM is essentially saying Sandra has no friends. We have not heard from any friends. Granted Sandra moved to a new area, but she lived in Quincy a long time and Hanson isn't that far from Quincy.
I only know of a few people that don't have friends, it is rare. These people tend to be quirky and abrasive, and a bit odd. By default, outsiders know little about them or what they do.
My point is that there is a small circle of acquaintances. There is no evidence of robbery, and if foul play is involved, the number of people close to Sandra to look at is small. Sandra hung out with her sister and cousin, and who else?
Is LE able to track the digital trail of the few people close to Sandra? Do they need a warrant to do this? Could LE get a warrant for digital trails of acquaintances without prior evidence linking these people to Sandra's location that night?