Well, none of the above, actually. Maybe she saw "something," recognized a voice she'd heard, but wasn't sure of the name or exact identity. Still think it could have been someone the girls met casually while jogging, which could have triggered MK's partial recollection.
OR, could be someone she did pretty much recognize, and family and LE hoped to convince that "someone" to give up without making their identity known publicly. Extended family? Suppose anything is possible.