BOSTON (CBSMiami/AP) —  The father of a man who was shot and killed by authorities in Florida while being questioned in the Boston Marathon bombing investigation has written to President Barack Obama, asking for help to find out what happened.

Abdulbaki Todashev says in his letter from Russia son Ibragim Todashev knew dead marathon suspect Tamerlan Tsarnaev  through boxing but had no connection to the bombing or any other crime. He says his son voluntarily went to an FBI office in Orlando to speak with agents four times before they showed up at his apartment May 22.

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Attorney Barry Cohen said Monday the elder Todashev fears a cover-up and wrote Obama one father to another to make sure that doesn’t happen.

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An Orlando prosecutor is investigating the death. An FBI spokeswoman won’t comment. The White House hasn’t answered an email seeking comment.

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