crimes "committed with a level of brutality and depravity not previously seen in Yugoslavia ... and are among the darkest days in modern European history." The judgment in Krstic's 2004 appeal upheld the lower court's finding that "Mladic directed the operation." The defense and prosecution "agreed that General Mladic was the main figure behind the killings." Mladic and his political boss, Radovan Karadzic, repeatedly emerge as the two central figures in the conduct of the 1992-95 Bosnian war, leading the meetings at which military strategy was decided and giving the orders to carry out their ambition of "cleansing" areas of non-Serbs. Judging from the Krstic case and other trials, the evidence against Mladic, the overall Bosnian Serb army commander, appears overwhelming. But legal experts said it must be put to the test against Mladic's defense team, and they cautioned against inferring guilt from the convictions of his subordinates. At question for the court to decide is whether Mladic was ultimately responsible, directly or indirectly, for the deliberate massacre at the U.N.-declared safe zone. Srebrenica is the most serious incident of the war for which he stands accused. The lengthy list of charges also includes ordering the four-year-long siege of Sarajevo. In all, about 100,000 people were killed in the war. In Belgrade, Mladic's lawyer said Monday he would appeal the order to extradite the 69-year-old former general to the tribunal in The Hague on the grounds of ill health. Mladic's son Darko said Sunday his father was not responsible for Srebrenica massacre and that he gave no orders for the killings. "Whatever was done behind his back, he has nothing to do with that," Darko Mladic told reporters in Belgrade, where the former general was taken following his capture last week. Even if proven true, Mladic could be held to account for war crimes. Earlier cases have established a principle of "command responsibility," holding that commanders are liable if they failed to prevent or punish illegal actions of their men. "You don't necessarily have to give direct orders," said Alison Smith, the legal Counsel for the Belgian-based group No Peace Without Justice. All together, 12 Bosnian Serbs, many of them senior officers, have been convicted of genocide, war crimes or crimes against humanity for Srebrenica. Besides the Karadzic case, another four trials of military men related to the massacre have yet to be completed. "The evidence strongly suggest that the criminal activity was being directed by some members of (Bosnian Serb army) Main Staff under the direction of Gen. Mladic," said the Krstic appeal. The International Criminal Tribunal for the former Yugoslavia was created in 1993 -- even before the Balkan wars reached their climax. The vast majority of the 161 people it indicted were Serbs, a fact that has prompted many Serbs to denounce the U.N. court as biased. Mladic and Karadzic were indicted after Srebrenica and both went into hiding. Karadzic was captured in 2008 and his trial is still in the early stages. In 2001