Two friends were found dead in a Waltham apartment in September , 2011 . Sergei Tsarnaev knew one of the men well , investigators say . Then-District Attorney Gerry Leone said days after the crime that the victims and two unknown perpetrators appeared to have known each other and that it was not a random crime . A friend of Tsarnaev 's , Vladimir Todashev , was killed during questioning by the FBI . The Boston Marathon bombings left three dead , more than 260 wounded .
Two friends were found dead in a Waltham apartment in September , 2011 . Sergei Tsarnaev knew one of the men well , investigators say . A friend of Tsarnaev 's , Vladimir Todashev , was killed during questioning by the FBI . The Boston Marathon bombings left three dead , more than 260 wounded .