Forensic clues are starting to emerge from the aftermath of the Boston Marathon bombing but there is still no evidence as to who was behind the deadly attack.<br /><br />The double bombing, which killed three people and injured more than 170 others, was the worst attack in the United States since September 11th.<br />...<br />No Comment | euronews: watch the international news without commentary | http://www.euronews.net/nocomment/
