Shouldn't Iraq bomb investigations be handled on a first come, first serve basis ?

It sounds as if Wolfowitz’ got bumped to the head of the line:
U.S. Detains 18 for Attack That Came Close to Wolfowitz
I sincerely hope that the bombing at the UN complex, police stations, Red Cross, and several mosques are receiving equal slices of the investagatorial pie.

What, specifically, in that article leads you to believe that particular attack was selected for investigation before others that you list? What makes you believe there’s any kind of investigation queue, or investagatorial priority, assigned to any individual attack?

Not much. It just struck me as odd that the break on this one should come first. You’d think a large blown up truck would be easier to trace than the peculiar blue paint on the side of a homemade pickup-trailer/rocket nest. Perhaps the investigators just got lucky here.