The father of a Canadian boxer who was killed by Russian security forces while fighting for an Islamic extremist group in Dagestan said he does not know if his son had any contact with one of the suspects in the Boston Marathon bombings.

Vitaly Plotnikov, whose son William was shot and killed in July 2012, said he had lost contact with his son when he left for Russia.

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Tamerlan Tsarnaev, one of the two Boston Marathon bombing suspects, has been linked in a Russian news agency report with having had contact with an ethnic Russian who resided in Toronto, but the Canadian man's dad says he has no idea if that's true. (Julia Malakie/Lowell Sun/Associated Press)

"Somebody is like, 'William boxer, Tamerlan boxer, maybe there [was] contact," Vitaly Plotnikov told CBC News. "I don't know. Maybe, maybe. I didn't get [any] news from William when he went to Dagestan. He never contacted me.

"Maybe William, online sometime speak with him or each other. I don't know. No idea, because William not speak with me. Never."

A Russian news agency recently reported that William Plotnikov, an ethnic Russian who resided in Toronto and was a Canadian citizen, may have had contact with Tamerlan Tsarnaev, who along with his brother are suspected in the April 15 bombings.

Tsarnaev spent six months in the Dagestan region in 2012, around the same time William Plotnikov was there.

Tamerlan and Dzhokhar Tsarnaev had roots in Dagestan and neighbouring Chechnya, but had lived in the U.S. for about a decade.

Just days after the Boston Marathon bombings, Tamerlan was killed in Boston in an exchange of gunfire with police. Dzhokhar is currently in custody, charged in the bombings that killed three people and wounded more than 200.

Vitaly Plotnikov said he did not know if his son had extremist views or when he may have adopted them.

He said his son was an accomplished boxer who suddenly converted to Islam around 2008, but talked little about his new religion.

"He had lots of friends and girlfriends. Suddenly finished. No friends, no father, no mother. Only room and pray. That’s it. What happened? Who can change his mind?"

Vitaly said that he and his wife went to Florida on vacation in 2010, while his son stayed in Toronto. But when they came back, his son had left a note that he had gone to France for Ramadan. They later found out he was in Russia.

With files from The Associated Press