FSS Colonel (ret.)
Vadim previously served as Putin's nuclear briefcase holder. He retired in order to join the private sector. When he died he was under house arrest for accepting bribes. His brother found him shot in the head in his kitchen.
Depending on the source (and the translation), the brother was either hiding in the bathroom when Vadim was shot, or he was using the bathroom and heard a shot. The first implies an attack on Vadim in his own home, while the second could have been a legitimate suicide.
Needless to say, the brother isn't exactly jumping at the chance to clarify either situation.