When it comes to the Boston Marathon bombing and Tamerlan Tsarnaev, the question has become this: what did the US government know about Tsarnaev, and when did they know it?  At first, it seemed as though the elder Tsarnaev brother flew under the radar, even after a warning to the FBI a few months before Tamerlan took a six-month trip to Russia for no apparent reason, leaving a wife and baby behind.  Now, though, the Washington Post reports that the Joint Terrorism Task Force got warned on Tsarnaev’s return that he had become radicalized — but that the person to whom the warning was delivered didn’t do anything with the data:

Nine months before the Boston Marathon bombing, a U.S. counterterrorism task force received a warning that a suspected militant had returned from a lengthy trip to Russia, U.S. officials said.

The warning was delivered to a single U.S. Customs and Border Protection official assigned to Boston’s Joint Terrorism Task Force, a cell of specialists from federal and local law enforcement agencies. The task force was part of a network of multi-agency organizations set up across the country after the Sept. 11, 2001, attacks to make sure that clues and tips were shared.

But officials said there is no indication that the unidentified customs officer provided the information to any other members of the task force, including FBI agents who had previously interviewed the militant. …

The disclosure — one of several to cause lawmakers to express concern about persistent gaps in U.S. counterterrorism procedures — came as U.S. officials revealed that the bombing suspects may have intended to carry out a follow-up attack in New York’s Times Square.

Just before this revelation, the head of American intelligence assured an intelligence conference that “the dots were connected”:

Congressmen are already lining up to label the Boston Marathon bombing as yet another failure of the U.S. intelligence community. The head of America’s 16 spy agencies has a response for the Capitol Hill critics: back off.

Director of National Intelligence James Clapper urged Americans today “not to hyperventilate for a while before we get all the facts.” In his most substantial public comments on the Boston attacks to date, provided at a suburban Washington intelligence conference, Clapper warned that finding the bombers in advance would require an invasion of Americans’ privacy by the government that citizens would likely find intolerable.

“The rules were abided by, as best as I can tell at this point,” he said at the confab, called the 12th Annual C4ISR Journal Conference. “The dots were connected.”

Well, except for that one about the radicalized Russian returning after leaving his wife and child for six months.  So what happened to the tip?

U.S. officials also said that the customs officer in Boston may have mentioned Tsarnaev’s return to FBI agents serving on the task force without creating a computer file to record the information had been shared.

Bear in mind too that by the time Tamerlan had returned, the CIA had already entered his name in the Terrorist Identities Datamart Environment (TIDE) database in late 2011.  Had the JTTF followed up on the tip at the time, they would have actually connected those dots — and might have at least been cognizant of Tsarnaev’s activities.  Would that have stopped the attack?  It’s impossible to know now, but if the Post’s report is correct, we can at least know that the dots weren’t all connected.

Perhaps the US will find a few more dots, if Dzhokhar Tsarnaev starts cooperating again.  Early this morning, the surviving suspect got transferred out of Beth Israel Deaconess Medical Center to the hospital at Fort Devens, which means he’s likely to survive to go to trial on terrorism and mass murder charges:

Security will be easier to structure at the decommissioned base, and it will also get the bomber out of the same hospital that is treating so many of his victims.