Reasons some may feel RL holds info or could be peripherally involved might include:
He WAS out driving that day, going to and from, so may have seen activity or person (s) of interest also outside around there at that time.
A neighbor came to his door around 6:30 asking if it was OK to search his property and they may have had additional conversation.
What neighbor found the girls? Could it be same one? If so, ironic.
Said neighbor may have seen activity or person (s) and mentioned to RL.
He has lived there more than 50 yrs, likely knows those nearby who have lived there too, present and past, and perhaps knows a lot of their personal info so may know something that way as in a link from one person to another including possible shady personalities or connections.
He may have had someone staying with him in Feb, or off and on, or in the past who could be involved somehow.
Perhaps someone borrowed his truck that day or on occasion in the past.
He may know who frequents the bridge, who hunts in the area or just likes to walk the woods.
Someone he knows in the area may have unusual interest in young girls or other traits or habits that are odd.
He may feel he strongly recognized BG and even told LE and could be fearful hence his serving time is warranted yes but also not entirely undesirable to him as it keeps him safe from harm until an arrest when perhaps he will get off on time served. (Sentence does seem a bit heavy handed to me.)
May have picked up a rider while he was leaving/returning that day.
May have seen a vehicle parked in the vicinity and possibly even approached driver inquiringly or had some interaction of sorts about it.
He may be suspicious of a neighbor and asked questions that caused the neighbor to share info that RL then shared with LE putting him at risk and thereby involving him.
He may have a friend or relative who visited day before, night before, that morning.
He may pay someone to do work for him on occasion and this person may be involved or brought someone along at times who may be.
He may know more about drug use or nefarious activity in the area than we would think!
He may have seen a car or person multiple times scouting the area but did not think much of it at the time.
Maybe he attends community meetings that bring him in contact with someone of interest.
Some one has done some work on his truck and been around the area?
May know transients in the area?
He likely knows delivery persons in the area if he sees them regularly OR may know of a delivery to the area That day, saw delivery truck, etc.
Many ways he cld be involved, not just that they were left on his land which was likely by happenstance I would think. IDK!!! Just thoughts!!!!
