William Plotnikov , a Dagestan insurgent fighting in the Russian region , was killed in May 2012 . CNN filed forms seeking use the fighter 's last name as his first name . Tsarnaev flew out of Dagestan two days after Plotnikov was killed and investigators have been looking into whether Tsarnaev left because of Plotnikov 's death , according to another source briefed on the investigation . Official to Tamerlan Tsarnaev : `` There 's no evidence why he wanted to change his name ''
William Plotnikov , a Dagestan insurgent fighting in the Russian region , was killed in May 2012 . CNN filed forms seeking use the fighter 's last name as his first name . Official to Tamerlan Tsarnaev : `` There 's no evidence why he wanted to change his name ''