Momir Nikolic, assistant commander for security and intelligence in the Bratunac Brigade, pleaded guilty in 2003 to charges of persecutions on political, racial and religious grounds.
He was initially sentenced to 27 years for his role in the organisation and coordination of the 1995 Srebrenica massacre, as well as subsequent human rights abuses in the towns of Potocari, Bratunac and Zvornik.
Under a plea deal, he testified at the trial of Vidoje Blagojevic and Dragan Jokic, who were also indicted for their roles in the killings in Srebrenica.
Nikolic appealed his sentence in 2003, and it was reduced to 20 years in March 2006 after the appeals chamber found that the ruling failed to take his cooperation with the prosecution into account.
The tribunal has ruled that the killing of Bosnian men and boys at Srebrenica was genocide, the only such classification from the 1992-1995 Bosnian war.
Around 25 other persons convicted by the Hague tribunal are in prisons in Austria, Britain, Denmark, Finland, France, Germany, Italy and Spain.
Sara Goodman is an IWPR reporter in The Hague.