Tamerlan Tsarnaev wife: The FBI wants to question Katherine Russell Tsarnaev, the wife of Boston Marathon bombing suspect. She says Tamerlan Tsarnaev was home caring for her toddler while she worked. Tamerlan Tsarnaev was killed in a shoot-out Friday.
Martin Richard, the 8-year-old boy killed in the Boston Marathon bomb attack, once held a sign that said 'peace' and 'no more hurting people.' Research finds a pattern of lessening violence as human history moves forward.
As authorities searched for suspects in the Boston Marathon bombing case, online amateurs used social media and other sites to crowdsource the investigation. But like citizen journalism, 'citizen law-enforcement' has its downsides.