[mhking]

Are there areas like that in the search perimeter?

Metro DC is incredibly transient. Add to that the 10-12 colleges in Metro, plus the thousands of tourists, and you have a formula that allows someone a huge sea of humanity to disappear in. And while he's operating quite a bit in the suburban areas, it is not unusual to see out of state/out of area license plates and think nothing of them.

While the notion of "neighborhood watch" would work in many other towns and areas of the country, the notion breaks down in any sort of moderate to heavily trafficed area in Metro DC.

Out of all the shooting vicinities, the only ones that would qualify within your parameters are the two in Fredericksburg. And even then with their proximity to the interstate, there would be less of an eye batted at any "unusual" vehicle there as well.

[BiffSchneider]

"you have a formula that allows someone a huge sea of humanity to disappear in"

In any sea of humanity, you always are going to have several neighbors. I'm in L.A., which is probably even more tightly packed than DC. If they were offering a $500,000 reward, and all you had to do to get it would be find a cream colored van with a ladder on it, people would look at all the vans with which they have contact, and I don't think it would be too long before it was found. This isn't just like Neighborhood Watch, this is more like the lottery.

So, I think the sniper has found some way to lessen the chances that someone else knows about or notices his vehicles.