In 1927, Leon Trotsky, a leading Russian revolutionary, was expelled from the Communist party and exiled from Russia on Stalin's orders.

After spending time in Turkey, France and Norway, Trotsky and his wider family eventually settled in Mexico.

Less than four years after arriving in Mexico, a Stalinist agent managed to infiltrate Trotsky's inner circle and used his trusted position to assassinate him.

His grandson, Esteban Volkov, who was living with him when he was killed, remembers his grandfather.

Witness is a World Service radio programme of the stories of our times told by the people who were there.