How long until we know?  —  It's been more than 24 hours since the explosions in Boston.  But while new details emerge by the hour, the question on so many people's minds remains unanswered: Who did it?  —  “The range of suspects and motives remains wide open,” FBI Special Agent Richard DesLauriers said …

Injured Saudi is a witness, not a suspect, in Boston bombing  —  U.S. law enforcement officials said Tuesday that a Saudi national injured in the Boston Marathon bombing is regarded as a witness, not a suspect.  —  The Saudi, who is recuperating at a Boston hospital, is in his 20s …

Militia Groups Denounce Boston Marathon Attack  —  Early speculation that militias were behind the bombings are “totally off-base,” says one leader.  “This was a target of civilians, which is reprehensible by every measure of what we hold to our values.”  —  Via: Adrees Latif / Reuters

Reinhart-Rogoff, Continued  —  I was going to post something sort of kind of defending Reinhart-Rogoff in the wake of the new revelations — not their results, which I never believed, nor their failure to carefully test their results for robustness, but rather their motives.

Envelope tests positive for ricin at Washington mail facility  —  Washington (CNN) — An envelope that tested positive for the deadly poison ricin was intercepted Tuesday afternoon at the U.S. Capitol's off-site mail facility in Washington, congressional and law enforcement sources tell CNN.

Bomb Details Emerge in Boston Case  —  BOSTON — The explosives used to kill three people and injure 176 at the Boston Marathon on Monday were likely some kind of “pressure-cooker” devices that sent sharp bits of shrapnel flying into victims in the vicinity of the blast, several law enforcement officials said Tuesday.

Why Boston Bombings Might Be Scarier Than 9/11  —  Killing Americans at play resonates differently than attacks on economic and military targets.  —  Call it “terrorism” if a label helps you make sense of this madness.  Find who did it and squash him—or them—with what President Obama called “the full weight of justice.”