What you just said, reminds me of a story in my (long) life. Don't know, why exactly. In any case, it's not your fault
!
When I was relative young (but already married with children), I worshiped an actor a little bit, whom I knew as an actor on TV. One day, I was invited to attend a theater performance in a city 60km away (1h driving time). On stage - I didn't know at all, that would happen - I heard a voice, which I knew from somewhere (like the Sheriff in case Abby/Libby re the audio). After some time (in the dark of the auditorium) I found the name of the "voice" within the playbill: excitingly, the voice belonged to my worshiped actor!
When back at home, within the next days I wrote a nice letter to him/the "voice", because I now finally had an address (address of theater in the city) and I confessed my admiration to him.
Some time later, it was a Saturday at noon, my doorbell was ringing and my husband went opening the door. I just had hair curlers all over the head and looked stupid and ugly. In this condition, I heard "the voice" at my door and looked down the stairs, overwhelmed and also ashamed by this visitor.
Short end of story: my husband invited him to come in and the worshiped actor, I only knew from TV and one single theater performance, sat on our couch for coffee and conversation. As he told, he had gotten my letter of admiration via his theater address and thought, when he had time, he would like to drive to my town exploring, which woman had such an admiration for him.
With distance to this event, I later thought, it was certainly an advantage to have a husband at home and to have an ugly look at the first glance (hair curlers on head). Who knows, what the actor's interest had been originally.
Transferred to the sad story of sweet Abby/Libby:
Maybe, they had had contact to someone, they admired. The contact wouldn't have been per letter of course, but per Internet somehow. What, if this
object of admiration (BG) had evil things in his mind (maybe, because it was a 13th of month or day before Valentin) and had ordered the girls to meet him, then surprised the girls with his appearance in an (ugly?) "disguise".
Perhaps that day he had a business meeting at a nearby town/plant/company; he had spare time between two appointments; he has a preference for remote areas and has excessive geographic knowledge; he has a preference for not age-appropriate adventures.
So, BG appeared on the bridge and when he came near to the girls, he said "Guys ....", because he knew, they were expecting him (with a different look) and he is verrry used to have people expecting him to appear.
WHY murder - I don't know and I will not understand forever.
All IMO MOO and thoughts.