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Boston Marathon Bombers: Criminal Minds

How two boys next door, who had lived in America for years, turned into alleged killers.
5:06 | 04/20/13

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Transcript for Boston Marathon Bombers: Criminal Minds
As you can see it's really begun to rain perhaps -- -- rain here in Boston as a suspect in Boston bombers their faces now tied to the carnage of the marathon. But what turned GO fire and temelin Sardinia into alleged terrorists I'm joined now by our new ABC news -- buying pets welcome -- -- Byron and remain. Tell us what -- these two -- Would you do tonight of Portugal the suspected bombers is -- two Brothers who came to the US in 2003. Like millions of immigrants they came here in search of a better life. But something. Went terribly wrong. Life and that never ever would imagine. That somehow. -- children of my -- would be associated with them. Tonight some family members of the two Brothers accused of the worst attack in the US since 9/11 are asking the question no one seemed to be able to answer tonight. Why there -- in Maryland says he thinks he knows. They provoked it being -- -- it. Hey -- -- those -- -- able to settle themselves. -- that young everything I can imagine. But what might have driven in 26 year old -- -- -- nine. In his nineteen year old brother Joseph -- to allegedly plan a pair of homemade bombs at the Boston Marathon. Given three negative wounding more than a 150. Those who -- -- saying. -- -- this is so Osaka. One game Connolly. When they can just like she's actually nothing happened and think she really did this was. Seems a heated this is -- dismissal or content to that some the most that happened in the past few weeks I guess that triggered -- like this I don't know. Does he like as of last Monday I would never assume you do summoned -- -- us. He's actually a very nice kid I got along with them very well. She said -- every day -- he has lived in Dagestan to promote part of Russia. A bloody conflict broke out. Aimed at radicalize Muslims. And sort of the father worked in law enforce the jurors that. -- these are Chechens were persecuted he says that's why we left there was a van had -- at one point there were about to annihilated its. They fled in by 2003. The family was living in the Boston area. The younger brother seemed to fit in do harm -- France took drama classes. I in my class -- hand -- -- an acting class together and he was always -- funny and and and you know he contributes did it never seemed like. There any warning signs. Playing several -- sports Joseph. Everywhere he was supposed to -- the American its former teacher Larry errands and talked with him about coming to live in America. He was so grateful to be here. And there was this whole idea of like you know this is the new life and I'm happy to be -- part of this he spoke you know. Like any other high school kid. After high school older brother Cameron -- attended Bunker Hill Community College but his real passion it was boxing. In 2010 he battled his way to New England heavyweight golden gloves championship but he apparently had an angry side. Reportedly arrested for assaulting his girlfriend. The charge was dismissed he was quoted as saying I don't have a single American friend. I don't understand. But younger brother Joseph -- seemed different the city of Cambridge honored him with -- merit award to attend the University of Massachusetts had dark. The boy's parents returned to Russia reached today by -- their mother says her sons were set up. And -- it is an Art -- who never seen nobody talked about that -- -- And today you to -- their father said he believed -- -- -- I have 100% confidence and -- he said. They normally don't let it. Very athletic -- Smart boy. Seemingly did not findings don't yet in the news network because it's not easy. Tonight a darker digital profile this emerging from saw these tweets over the past weeks never underestimate the rebel with a -- that's. Death is a destroyer of all pleasures a decade in America already. I want out. Well the day of the Boston Marathon each week it ain't no love at the heart of the city stay safe people -- retirement line. He's believed to have spent the first six months of last year in Russia investigators are trying to find out what he was doing name. To -- trying to find answers to this -- FBI investigators removed a computer from the New Jersey home of the suspect's sister. But the suspect's aunt insisted their online lives only show they were Brothers doing what most Americans do out of curiosity. Not maps. As for those surviving brother he will soon face his day in court in -- that is today the people of Boston. Are really looking forward. Captioned in English at home.

This transcript has been automatically generated and may not be 100% accurate.

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