Instapundit recalls that the Washington snipers were busted four years ago. An excellent example of the unorganized militia at work. As I recall, the police had gotten their IDs (not very hard, after they asked for cash to be wired to an account one owned) and license plate.
The police wanted to keep it quiet, but mistakenly broadcast it on an unencrypted radio channel. Reporters got ahold of it and reported it. A truckdriver, keeping his eyes open, spotted their car and called police.
Going by memory here, but the citizenry did a much more credible job than law enforcement. Local police had set up a hot line for sniper reports. When the real sniper called in with his demands, they repeatedly hung up on him. When he called the police directly, they told him all such calls must go to the hotline. He finally called a clergyman and got HIM to call, figuring they might at least listen to a minister, which they finally did. Then the FBI profilers had their say: the sniper was a young caucasian loner, who'd recently experienced some traumatic event. Wrong on everything.