After fully an hour of getting the run around or being given numbers that don't work, I gave up on phoning the DC area police or the FBI about a suggestion on what might be done to catch the sniper.
There would have to be considerable preparation and cooperation from the population and the radio stations. The idea is to get the stations set up to take automatic interrupt flashes when there is a shooting and a program to get everyone to keep their radio on.
When the news of a new shooting come on, have everyone put on flashers and stop, creating an instant all over roadblock to prevent the sniper from getting very far from the crime location. The stopped people could write down the licenses of the car in front of them as well as any cars that were still trying to move on shoulders and such.
I know the police are setting up roadblocks, but the blocks take too much time resulting in a very wide area with too many leaks in it. (Soon as the police decided how far out they wanted things tied up, they could release traffic in areas well outside where the latest shooting took place.)
This solution is not perfect of course. Stopping might result in too many wrecks.
But it would be a heck of a lot faster than setting up roadblocks, and the area they have to cover goes up as the square of the time. Stopping traffic within two minutes of a shot would keep the search area down to a few square miles And while it would be a bit of trouble, people are looking for any way to help solve this set of crimes and might be quite willing to help by keeping the sniper from getting away.
This assumes, of course, that he is in a road vehicle and not on a bike or something.
If anyone can figure out how to get this in the hands of someone in the FBI or one of the DC area police, please do.
And post any suggestions or holes you can see in the concept. There may be a fatal one I didn't think about.