(long-winded post ahead, but I'll try to stay within ToS)
MOO is there's a possibility he was able to lurk, and maybe even lured them somehow. I'm leaning towards lurk on a SM site or multiple sites, MSM reports indicate Libby had multiple SM accounts. It's pure speculation on mine or others' parts, but it's perfectly plausible.
MOO is at the very least, the perp knew Delphi schools had the day off. Perp knew the area where he was going to do his misdeeds that day, perhaps had visited the area before. He lurks on SM, seeing who checks in to the trail/park/bridge area, while hiding near or at the spot where the girls were killed (pure speculation on my part, for all I know he was in a vehicle in the cemetery when the girls got to the trail head). Libby 'checks in' on one or more SM accounts, or at the very least (and this is a big one) the perp saw the first image she posted (the one from the NW end of the bridge), then the one of Abby which uploaded at 2:07PM.
Far as the perp taking photographs or video, folks here speculated early on that could have happened, after all, how many cases here at WS have we seen where perps take images of their victims? Not many, but there are quite a few cases of serial killers doing just that, going all the back to the 70's.
After this case hit the news, I researched cases where LE were frustrated by SM, and how often it's used these days in crimes. Some of the more popular sites are based at various places around the world, so it's very difficult for LE to get warrants and court orders to do searches of users of those sites. SnapChat is based in Canada. SnapChat is notorious for requiring very little information to become a member. Those two factors alone have made it difficult for LE in other countries to get information off of SnapChat servers, although SC's management have been more cooperative in recent years, after balking at allowing LE outside of Canada to have access to their information the first several years they were in business.
Switching gears, I keep going back to other cases which have been covered, in-depth, here at WS. The Israel Keyes case keeps popping into my head, as I follow these threads about the Delphi case. I've watched a few YouTube videos about him, and, as many here have noted, when interviewed he was calm and downright friendly with the investigators, at least to a certain point, while at the same time elusive about any details of murders he was involved in. He explained his deeds in a manner which someone might order coffee, cool as a cucumber. Yet Keyes, like all of these other freak killers, was a control freak of the worst order, but in his case he was able to keep it under control to some degree, living a double life.
Keyes admitted to using Google to search for victims, surveil the areas he would abduct people, etc. These killings were after the murders in the parks he'd done when he was younger, Keyes (like so many other serial killers) 'graduated' to more sophisticated crimes. It was never revealed how he was able to do this w/o being detected, Keyes started using his home computer for searches regarding his own killings only in the months previous to when he was arrested in Texas. He got sloppy, as they say, and he admitted as such. So the FBI had only 'x' number of months' worth of internet activity to go by, in their case against him, as he'd used methods of using the internet known only to him up to that point, and now he's dead.
So if this killer used SM, they might have been able to do it w/o anyone being able to attach an e-mail, IP address, etc., to them, specifically.
SM or no use of SM, either way, I'm working off the assumption this killer is much more sophisticated, and smarter, than a lot of folks first believed. I'm leaning towards SM, this killer was looking for a certain demographic to abduct, and perhaps was looking for two victims. How did he know there were two victims at the bridge, that day? The image uploaded at 2:07 PM to SC.revealed two people were making their way to the SE end of the bridge, probably both juveniles, with noone behind them.
In my mind, I see BG either A) At the final killing spot, either surveilling the bridge or doing that and checking a smart phone, or B) At the cemetery, at the back of it, in a vehicle. I don't know if the drive into the trailhead area is visible from there, but at any rate I see BG possibly at the cemetery, in a vehicle, checking SM.
JMO
