Bosnian Serb war commander Radovan Karadzic begins his defense Tuesday at the U.N. Yugoslav war crimes tribunal in The Hague.

Karadzic is accused of masterminding the massacre of almost 8,000 Muslim men and boys in the Bosnian town of Srebrenica in July 1995. He is also accused of responsibility for the three-year siege of the Bosnian capital Sarajevo between 1992 and 1995.

Karadzic denies the charges against him. His attorney has contested the Srebrenica death toll, saying it is far lower than the official estimate, and says his client was not aware that executions were going to take place after the Muslim men were rounded up.

Karadzic spent 13 years on the run after being indicted by the international war crimes tribunal. He was found and arrested in 2008.

Also in the Hague Tuesday, the final suspect for the war crimes tribunal begins his trial. Goran Hadzic, detained in 2011, is accused of killings and forced deportations during the four-year war in Croatia that ended in 1995.