Sergei Viktorovich Skripal is a former Russian military intelligence officer who acted as a double agent for the United Kingdom's intelligence services during the 1990s and early 2000s. In December 2004, he was arrested by Russia's Federal Security Service (FSB) and later tried, convicted of high treason, and sentenced to 13 years in prison. He settled in the United Kingdom in 2010 following the Illegals Programme spy swap. He holds both Russian and British citizenship.