Viktor Bout, one of the world's most infamous arms dealers, has been released from US custody. Bout, also known as the Merchant of Death, was released as part of a prisoner exchange with US basketball star Brittney Griner. He was conscripted into the Soviet Army when he was 18 years old and while Bout insists he was never a spy, it has been claimed he once worked for the GRU. "Viktor Bout, in my eyes, is one of the most dangerous men on the face of the Earth," Michael Braun, the former chief of operations for the US Drug Enforcement Administration, said. Bout was extradited from Thailand to the US in 2010 after a sting operation by the US Drug Enforcement Agency two years earlier. He was sentenced to 25 years in prison in April 2012 after being found guilty of conspiracy to kill Americans and US officials.