"The older brother appeared to be the more radicalized of the two and was the one that drove the need to conduct the attack," said Seth Jones, a counter-terrorism expert at the Rand Corporation. Authorities said the younger brother told the FBI that he and his brother were inspired by the anti-US internet preaching of the radical cleric, Anwar al-Awlaki.
*Even though the American-born al Qaeda figure was killed in a US drone strike more than a year and a half ago, his words apparently still have great power, condemning the US actions in Iraq and Afghanistan, which the brother said became their motive," Jones said.
Tamerlan posted a video on his own YouTube channel, of a Chechen rebel leader threatening death to anyone who helps the infidels. That leader was killed by the Russians last year.
And it was on the Internet, Dzhokhar told FBI agents, that they learned how to make a bomb with a pressure cooker--all found in an Al Qaeda online magazine called Inspire. He told the FBI they never even tested the bombs before detonating them last week.
" What's disturbing about that is people are getting smarter about building easily manufactured bombs and then targeting sights in the US," Jones said.
Federal agents continue to search the Boston area for more bombs, but none has been found so far. One question that remains unanswered: What were the brothers planning to do next?
The man whose SUV was stolen by the two brothers as they allegedly fled the fatal shooting of an MIT police officer told authorities that he may have heard one of the suspects say "Manhattan" as they spoke in a foreign language.
The comment prompted a string of searches the next day, taking investigators to Connecticut as they looked for a Honda and searched trains. However, the search came up empty and it is not even clear the word was spoken by the suspects.
Police Commissioner Ray Kelly said the victim "heard them speaking in a foreign language and may have picked up the word Manhattan, but that is not at all clear at this time."
Today, NYPD spokesman Paul Browne said "No evidence they were headed our way. These stories were conflated with bits of information badly misinterpreted."