Former FBI Assistant Director Thomas Fuentes and CNN National Security Analyst Fran Townsend explain what evidence investigators could use to find who's responsible for the Boston bombings.
If you have information about the attack, call the Boston crime tips hotline at 800-494-TIPS.
Anderson Cooper goes beyond the headlines to tell stories from many points of view, so you can make up your own mind about the news. Tune in weeknights at 8 and 10 ET on CNN.
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