Prosecutor Ives is spot-on with the tower stuff, and besides, someone could have an alibi or false alibi as to why their cell phone was in, say, that area that day. There's also the issue of IN 25 going through there, that could wreak havoc on cell tower data.
BG could have a burner phone, for all we know, and/or didn't have a phone on or even near him at the time of the murders.
A phone usually indicates where the owner is. So he could have merely left his own phone at home, or in a car parked next to his house, or elsewhere. The phone creates an alibi, too. This is why I think no GPS devices of his were in the proximity to the bridge, or else, he had full right to keep them there.
This is the guy who knows about tracking cellphones. And about tracking DNA. This alone puts him out of general group. (I know many truck drivers, however, who read a lot and are very bright, just working the job because the pay is OK.)
I think that BG is in 35-50 group, but the knowledge of cellphones and DNA theoretically puts him in a younger group, hence, I am slightly confused.
Maybe he is into genealogy? As I mentioned, his DNA knowledge predates GSK publications, so either he knew of such work being done (i.e. LE world), or, he himself could be into genealogy. Genealogists usually are on forums where all these things are discussed, so they know a lot.
That could explain his presence at the cemetery, btw. Tracking not a family grave, but some grave yet not in Find-a-grave database.