There's an angle that we've been overlooking in regards to the cell phone...
I've seen people on here saying that GR couldn't have used the app because the phone was found in an dead signal zone.
I've seen others mention that the phone was found just outside of the dead-signal zone.
But I think about it, and that could be a clue that rules out another aspect of this case.
Early on, many were under the assumption that she had run away with someone from out of the area, and may have ditched her phone.
That's a highly unlikely circumstance given the type of person that Jennifer was, and the love that she had for her children.
But I thought more into, and it dawned on me... the location.
It's a dead-signal zone.
If the perpetrator was from outside of the area, it's highly unlikely that they would spend an hour or so looking for a dead signal zone to toss the phone.
The fact that the phone was found just outside of a dead signal zone could indicate that it was tossed believing that they were still in range of the dead signal zone, so as not to be found.
Of all the places for one to ditch the phone, especially on Route 23, the perp ditched it in an area where people in the past have complained of bad phone reception... which indicates to me... it's someone local... and not someone who came to the area from outside of the area for Jennifer to "run away" with.
Someone who was familiar enough with that area and that particular stretch of 23 having a long history of being a dead signal zone because of the hills blocking the cell tower signals in that stretch.
It's possible that 23 was the route of choice, because of the dead signal zones along it.
It's very possible that the phone was ditched where it was because the person planned to move to higher ground up a hill (possibly up Moon Hill Road), which would render a signal and the ability to track the route.
So it's possible that the phone was ditched first at the Moon Hill Road Intersection, then moving up Moon Hill Road to take the back roads (possibly to Fred Stewart Road to Center Road), so as not to be seen on the main roadway.
Dispose of Jennifer's body, and then head East on Center Road, turn right, then head south.
Turn right at the SR-23/Reservoir Hill Road intersection, pass the reservoir and head down Reservoir Hill Road back to Moon Hill/Blackman Road.