I wonder if the writings of Alisa Ganieva might give some clue as to motive. From the wiki:
"She moved with her family to Dagestan and attended school in Makhachkala...Her debut novel "Salaam, Dalgat!" describes the everyday life of Dagestani youth in the cities and shows the decay of traditional life...
Here was a statement from the Head of the Chechen Republic Ramzan Kadyrov--made on Instagram before the younger brother was caught:
"Tragic events happened in Boston. As a result of a
terrorist attack, people were killed. We already expressed our
condolences to the residents of the city and to the people of America.
Today, as the media report, a certain Tsarnaev was killed during a
detention attempt. It would be logical if he was detained and an
investigation was conducted, all the circumstances and degree of his
guilt explained. Apparently, the special forces needed a result at any
price to calm society."
I can't help but wonder if they were radicalized by this group: http://en.wikipedia.org/wiki/Shariat_Jamaat
Nice to see law enforcement being cheered for once. The parade of vehicles--that was the end of the marathon--I consider that
day Patriots Day--and we are all Bostonians now.