The DC Sniper killings were straight out of the Al Qaeda terror manual found in Afghanistan. Some of the terror techniques were published in an article (I think I found it linked from the news articles here on AR15) many months before those attacks.
The article was
Homeland Insecurity, by Joseph Farah of World Net Daily, September 4, 2002
In it he quoted the manual as saying (among other things)
-using pickup trucks with shooters concealed in the bed of the trucks;
-using motorcycles as a shooting platform for drive-bys and assassinations;
-execution of prisoners;
-ambushes of law-enforcement officers;
-residential assassinations;
-assassination on a golf course using a rocket-propelled grenade and rifle fire;
-drive-up kidnapping of target walking on a street;
-use of tunnels, storm drains and sewers for infiltration during urban raids;
-rappelling from rooftops of buildings to make entry on upper floors;
-use of motorcycles for grenade attacks; and
-raids on buildings with large numbers of occupants – perhaps schools or office buildings.
The Beltway Snipers were from Tacoma, WA, where a number of people were arrested by the FBI for terror plot charges, I think from the same Mosque as the snipers attended.
Draw your own conclusions.