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Motivations behind suspect Tamerlan Tsarnaev's attacks are still unknown. But, his boxing trainer says he knows why he might have done it.
The former boxing trainer of Tsarnaev, John Allan, says he was "frustrated" with citizenship rules. Former CNN reporter and Entertainment Tonight host, Rob Marciano, speaks to Allan.
We've seen him on surveillance video, but we've rarely heard him. Watch and listen to newly discovered video of Dzhokhar Tsarnaev.
The video, posted on Twitter in March, shows Boston Marathon bombing suspect Tsarnaev playing with his niece.
The mysterious killing of an 8-year-old girl has shaken a small community in California. CNN's Paul Vercammen reports.
Dzhokhar Tsarnaev was charged with one count of using and conspiring to use a weapon of mass destruction resulting in death and one count of malicious destruction of property by means of an explosive device resulting in death, according to a statement from the Justice Department. SEE THE CHARGES
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CNN's Joe Johns looks at the order of events outlined in court documents filed against the surviving Boston bombing suspect.
CNN's Tom Foreman breaks down recently released details of the Tsarnaev brothers' bombing of the Boston Marathon. (VIDEO)
RELATED STORY: Federal charges filed against Boston bombing suspect
Watertown, Massachusetts Police Chief Edward Deveau walks CNN's Wolf Blitzer through the series of events surrounding the Boston bombing suspects.
FULL INTERVIEW:
RELATED STORY: Terror, murder charges could be filed against Boston suspect
The FBI released photos and video of two suspects in the Boston Marathon terror attack and are asking the public for help identifying them.
If you have any tips for the FBI, call 1-800-CALL-FBI or go to bostonmarathontips.fbi.gov.
RELATED STORY: FBI releases photos, video of Boston bomb suspects
SEE ALSO: Photos: Boston bombing suspects
Dr. David King had finished running the Boston Marathon when the bombs went off, and he rushed to the hospital to help.
CNN's Chris Lawrence takes a look at how investigators are piecing together clues in the Boston Marathon bombings.
RELATED STORY: Healing in Boston as investigators seek 2 seen near bombing
CNN's Tom Foreman and former FBI assistant director Tom Fuentes discuss three critical time periods in the investigation into Monday's Boston Marathon terror attack.
RELATED: Photos of evidence