We have managed to narrow down the origin of the "federal law enforcement source" who told CNN's Fran Townsend on a Wednesday afternoon full of conflicting reports that there had been an arrest in the Boston Marathon case. The leak likely came from the FBI, although, really, the FBI wasn't too pleased about the "widespread reporting" with "unintended consequences." So maybe it was the Secret Service. Or the Bureau of Alcohol, Tobacco, and Firearms. Or Immigration, or Customs, or Homeland Security. Hell, maybe that "one law enforcement source in Boston" who told CNN's John King about the "game changer" arrest worked for the transportation authority cops. Really, on a day when confusion reigned, anonymous sourcing could have come from one of dozens of organizations and agencies and elected officials' offices involved in some part of the investigation. Here's the scope of what "law enforcement sources" look like in this case:
The Federal Bureau of Investigation (top right) is leading the effort. It has "hundreds of agents" involved in the investigation, both in Boston and the Boston area and at its headquarters in Quantico, Virginia. It is possible that one of those hundreds of agents in any of the locations was CNN's source — or one of its 36,000 other employees scattered around the world. The FBI is also a subset of the Department of Justice (top center), which itself employs thousands of people.