The investigation into the hacking of Democratic National Committee computers during the US election campaign continues to haunt international politics. Was Russia responsible for the hack? The US Secret Services say this is now beyond doubt. Just before he left office President Obama hit back with a series of retaliatory measures against Russia. Those measures included a range of sanctions against institutions and people: two intelligence agencies, four senior intelligence officials, 35 diplomats, three tech companies. They also targeted a man who was infamous in tech security circles. His trade name is Slavik. Ed Butler hears the remarkable story behind Slavik's years spent attacking and compromising the servers of international banks and what it all reveals about Russian cyber-espionage.

(Picture: An employee walking behind a glass wall with machine coding symbols at the headquarters of Internet security giant Kaspersky in Moscow. Credit: KIRILL KUDRYAVTSEV/AFP/Getty Images)