There are cameras everywhere. The FBI has access to all of them. They have access to records of your phone pinging cell towers. The FBI could find who delivered those pallets of bricks, today. But they are not.
Incompetence? Malice? It's really a toss up.
I remember learning it was illegal to question the Holocaust in Europe in 9th grade. I knew then that it didn't happen. I just didn't understand why that was such a big deal at the time.