Former FBI director Robert Mueller told an American Bar Association breakfast today that the government's dragnet collection of US phone records assisted in the Boston marathon bombing investigation. The Intercept reports:

Mueller cited the example of the Boston Marathon bombing as evidence that bulk collection is important, saying that analysis of metadata was able to rule out potential associates of the Tsarnaev brothers. “They had additional IEDs [Improvised Explosive Devices],” Mueller said, adding that bulk collection helped prevent a second attack.

Metadata collection, he said, “is tremendously helpful in identifying contacts.”

According to this reporter, Mueller appears to say analysis of the brothers' phone records helped investigators determine that the Tsarnaevs acted alone. Strangely enough, the Department of Justice said something very different in a brief in US v. Tsarnaev. In a May 2014 motion, the US Attorney's office in Massachusetts told a federal court that:

searches of the Tsarnaevs’ residences, three vehicles, and other locations associated with them yielded virtually no traces of black powder, again strongly suggesting that others had built, or at least helped the Tsarnaevs build, the bombs.

Mueller implies the phone records helped the FBI determine the brothers acted alone. The DOJ says evidence "strongly suggest[s]" that the Tsarnaevs didn't build the bombs, or at least had outside help. Which is it?

Either way, Mueller is wrong. Even if the phone records dragnet helped the FBI determine something, whatever the FBI learned from those records could have easily been discovered absent the nationwide phone surveillance program.

That's because when someone is accused of blowing up a sporting event, it's extremely easy for the government to obtain their phone records. It would have been a small matter for the government to obtain the phone records of everyone the brothers had talked to, as well, without the unconstitutional dragnet.

In fact, local prosecutors investigating routine cases like burglary and check fraud can obtain call records with a simple subpoena in many states. It's hardly a big national security surveillance power. Prosecutors at all levels obtain cell phone call records with simple subpoenas every day, all throughout the United States.

So no, Mr. Mueller. Even if what you've said about the Tsarnaevs acting alone is true—and the DOJ appears to disagree—what you've said about the phone dragnet is completely false.