In 2002, the UN Secretary-General Kofi Annan appointed him as Deputy Prosecutor for the Special Court for Sierra Leone, at the level of an Assistant Secretary-General, and in 2005 promoted him to the post of Chief Prosecutor at the higher level of Under Secretary-General. Silva brought about the arrest of Charles Taylor, former President of Liberia, who was convicted of war crimes at the Hague in 2011.
In 2002, Kofi Annan, UN Secretary-General, appointed Silva as Deputy Prosecutor for the Special Court for Sierra Leone at Assistant Secretary-General level and promoted him to Chief Prosecutor at Under Secretary-General level in 2005. Silva played a role in capturing Charles Taylor, former President of Liberia, who was convicted of war crimes by The Hague in 2011.