Joe Biden speaks at memorial for Boston police officer

US Vice President Joe Biden today spoke at the memorial for Sean Collier, a police officer killed in the search for the Boston marathon suspects.

Biden commended all who attended the memorial, saying that people's determination "resonated around the world".

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Boston bombs 'remote trigger'

US investigators have revealed the two bombs that went off at the Boston Marathon were detonated with the kind of remote control device used for a toy car.