A rough timeline for your consideration:
03/30/2011 Russa tells FBI: Tamerlan Tsarnaev is a radicalised Islamicist
06/09/2011 Napolitano: No "Logic" In Profiling Muslim Men Under The Age Of 35
02/15/2012 FBI Purges Training Material of “Anti-Islam” Documents
10/01/2012 Tsarnaev enters U.S. after six-month trip to area bordering terror hotbed Chechnya
10/31/2012 Russia asks FBI to investigate Tsarnaev -- the FBI never responded
03/20/2013 Special Travel Benefit for Saudis a "Slap in the Face"
03/21/2013 Imam From Radical Mosque Invited to Speak at Obama’s Boston Service
04/15/2013 Tsarnaev brothers detonate IEDs at Boston Marathon, killing 3 and wounding 200
04/21/2013 'Police may never question marathon bombing suspect', says the Mayor of Boston
The President asserts that officials don't know the bombers' motives and that he'll get to the bottom of it.
Here's a tip that should save him some time: Jihad.
As Andrew McCarthy adroitly notes, no matter how many times the Obama administration tries, "Jihad will not be wished away."
And, as an aside, we still have no earthly idea what Barack Obama did before, during and after the attacks in Benghazi that killed four Americans including an Ambassador.