He (or she or they) is very clever, very cunning. He's plotting, planning, thinking things through, making sure he can get in, make his shot & escape unnoticed. And now he's playing mindgames with the cops and all of us. Chilling.
The guy is writing the new textbook on terrorism. Sort of an update on the old Mafia hitmen-out of towner, unknown, work alone, plain vanilla, one shot, move on, next contract. We just don't know the motivation.
Using some old spycraft too. Hide in plain sight, set no pattern, simple weapon, walk or bike away.
The guy's visited millions of dollars in losses to the DC area for about $13 worth of ammo and $ 189.00 worth of gun.