As US government prosecutors prepare to file charges against 19-year-old Dzhokhar Tsarnaev in connection with the deadly twin bomb blasts at the Boston Marathon, there are numerous unanswered questions surrounding the attack and about the two brothers who are believed to have carried out.
Were more attacks being planned?
Were Tsarnaev and his brother hoping to carry out more attacks and if so where and when?
Why was The Boston Marathon chosen?
The motive behind the bombing at the Boston Marathon is a big question: Why would the brothers do this?
Were any Islamist militant groups involved?
It is unclear if Tamerlan had contact with Islamist militant groups in the restive and predominantly Muslim Caucasus region, which have been blamed for a variety of terrorist acts within Russia.
What happened after FBI 2011 interviewed Tamerlan Tsarnaev in 20111?
FBI says it contacted him, but did not learn of the identities of the bombing suspects, Tamerlan and his brother, Dzhokhar, until Friday, the day Tamerlan was killed..
Should the surviving suspect be treated as an enemy combatant?
We've learned aboot a six-month trip that Tamerlan Tsarnaev took in January 2012, traveling first to Moscow, then to Dagestan and Chechnya, according to his parents.
Were all the bombs homemade, or were others explosives involved?
Federal officials examining the bomb residue collected in Boston have described the bombs – pressure-cookers packed with explosives and shrapnel – as relatively simple in their basic design, but with sophisticated components, including what appeared to be an electronic detonation mechanism capable of being triggered by cellular phones.
Why didn’t the brothers flee after the bombings?
Investigators continue to probe Dzhokhar's behavior after he returned to the campus of the University of Massachusetts at Dartmouth on Tuesday and resumed the life of a student after allegedly dropping a bomb-filled knapsack into a crowd watching the marathon.
How did Tamerlan Tsarnaev die?
Tamerlan Tsarnaev was killed during a ferocious gun-battle early Friday with Watertown, Mass., police, but officials have not yet explained how he actually died.