In an article posted the morning of February 14th, we're provided some extremely interesting or valuable information about the case that to my knowledge is not mentioned anywhere else:
http://wlfi.com/2017/02/14/community-continues-to-search-for-missing-teens-in-carroll-county/
At 1:20, the grandfather mentions that the phone has been "pinging around town" but the last ping was "5-6 hours ago". There is no timestamp on the interview, but it's clearly dark and appears to be taken the night of February 13th where no foul play is suspected (the mother is interviewed, and simply worried about the cold).
Given the fact that it's dark in the video, we can assume it's somewhere around say 9pm on February 13. Five to six hours earlier would mean the last pings were around 4-5pm. If we assume BG confronted the girls soon after the photos on the bridge -- say around 3pm -- that would mean the phone was still alive and working for at least an hour or more after the assault. The grandfather mentions he has confirmation of texts being received, but unread, which would also support this.
This is an extremely strong indication that BG did
not take the phone, turn it off, throw it in the water, etc. prior to the crime. If Abby and Libby were going out to take photos, it's also reasonable to assume they fully charged the phone before the trip. The only way a fully-charged phone is going to die within a few hours is if it's disabled (e.g., thrown into the water after the crime) or if it's doing something battery-intensive like recording audio/video. Since LE mentioned the phone was found on Libby's body (probably in a coat pocket), we can assume it wasn't found in the water.
To support this further, it's worth noting that (to my knowledge) LE very deliberately stated that BG is not necessarily the same person in the audio clip. This simply means in that clip, you can't see him say anything. One way to explain this would be if Libby started recording but as he approached, quickly put the phone away in her pocket without him noticing, and left it recording.
Like most of us, I'm convinced that phone recording is going to contain horrific content of nightmares. However, I don't think it's going to be particularly useful evidence in finding the murderer(s), because it really seems to me LE is stumped.
