It's interesting that Lori's neighbor in Rexburg (Seth) knew in advance that JJ was leaving (purportedly to be with his grandma), so likely he didn't suspect anything. I'm guessing that Seth did not see JJ after September 23. If JJ had been there much later, the neighbor would probably have noticed.
Seth doesn't mention Chad. Was he ever seen at Lori's place? It was mentioned earlier that Lori and Chad had fled by the time the police arrived, but it was rather Lori and Alex. Did they leave in one vehicle? When did Chad go on the run? Did he disappear from his home? When did he join Lori?
Alex was likely already a part of a few investigations in Arizona at the time the police searched his Rexburg appartment.
Missing Idaho children’s mom fled the night before FBI raided home, neighbor says