A new figure has emerged in the story of a Boston bomber's conversion to violent extremist Islam - a 23-year-old boxer from Canada who Tamerlan Tsarnaev met online and may have visited during his trip to Russia last year. William Plotnikov, a Muslim convert from Toronto, could have spurred Tsarnaev to direct his against the United States, new reports reveal. The Russian newspaper Novaya Gazeta reports that Tamerlan went to Dagestan - a Russia republic torn by jihadist terrorism - to join an Islamic militia and fight against Russian forces in July 2012. One day after Plotnikov was killed by Russian security forces, Tamerlan fled to Moscow. The next day he was back to the United States. Another contact Tamerlan had in Dagestan - Makhmud Mansur Nidal, 19 - was also killed by Russian forces during his six-month visit to to the war-torn region. Tamerlan's family blames a red-haired Armenian convert known only as 'Misha' for turning the 26-year-old to extremist Islam. Howeve