The problem is, the shooter (or shooters) do not fit the normal pyscho killer profile. The profile they most closely fit is that of guerilla attacks.
Bingo. Agree, all the more reason to consider the Navy Seal angle/sony playstation game socom:Navy Seals/Navy Seals movie with sniper nickname of God/
If there is anything to this angle, cops would study these and try to anticipate killer's thinking.
I am as positive as I can be that this is not 2 shooters also.