AMSTERDAM -- A Croatian Serb convicted of ethnic cleansing after leading a brutal revolt during the Balkan wars committed suicide in prison, the UN tribunal said yesterday, a setback for prosecutors counting on his testimony in other war crimes cases.
Milan Babic showed no sign of despair before he killed himself Sunday evening, a tribunal spokeswoman said. But his suicide came three weeks after he reaffirmed his remorse for his crimes, telling a tribunal that his guilt was a ''pain that I have to live with for the rest of my life."
Once a close associate of Slobodan Milosevic, president of the former Yugoslavia, Babic was considered an ''insider" with special knowledge of the workings of Milosevic's regime, and prosecutors put him on the stand for three weeks of dramatic testimony against his former mentor in 2002.
His death will be a setback for UN prosecutors who had planned to summon him as a witness in as many as three more war crimes cases. He had agreed to testify against his former comrades as part of a plea bargain.
Babic, 50, who was sentenced in 2004 to 13 years' imprisonment, was found dead at 6:30 p.m. at the UN detention center in Scheveningen, a few miles from the war crimes tribunal in The Hague.
His body was discovered during a routine half-hourly monitoring of his cell, tribunal spokeswoman Alexandra Milenov said.
''He gave no indication he was contemplating such a move," Milenov said. ''There was nothing unusual in his demeanor."
The tribunal said it was launching an inquiry.
His was the second suicide at the detention unit, following the 1998 death of Slavko Dokmanovic, another Croatian Serb leader.
Rasim Ljajic, chief of Serbia-Montenegro's government agency for cooperation with The Hague tribunal, said Babic's death probably would deepen the distrust most Serbs have for the UN tribunal, created in 1993 to try those responsible for massacres and atrocities being committed during Yugoslavia's violent breakup.
''This second case of suicide certainly won't help our public's perception about the tribunal," he said.
The Association of Serbs from the Croatian Krajina, a Belgrade-based group, said Babic's suicide indicated that the tribunal ''obtains its confessions through extraordinary pressures and lies," and that Babic ''resorted to the only solution he could in defense of human dignity."
Babic, a former dentist, was a ranking Croatian Serb leader when the Serb minority revolted after Croatia declared independence from Yugoslavia in 1991, setting off a war that lasted until 1995.
Babic was accused, along with Milosevic, of being part of a conspiracy to clear roughly one-third of Croatia of non-Serbs and incorporate that area into an ethnically pure Serbian state.
From August to December 1991, Croatian Serbs killed hundreds of Muslims and Croats in the Serb-dominated Krajina region and drove 80,000 from their homes. Babic later testified that Serbian secret police under Milosevic's authority were the driving force behind the ethnic cleansing.
Babic surrendered in 2003, a few weeks after the tribunal issued its indictment, and pleaded guilty to one count of crimes against humanity. His cooperation in future trials was part of a plea bargain in which prosecutors dropped four other charges of murder, cruelty, and the wanton destruction of villages during the war in Croatia.
In his plea agreement, Babic said he knew nothing of the murders of non-Serbs until many years later and had no knowledge at the time of the extent of the crimes being committed by Serb forces.
Babic's testimony against Milosevic provided a dramatic highlight to a trial that has gone on for more than four years.
During his testimony, Babic requested that his identity be concealed, but he later asked to have the secrecy lifted so that his confrontation with Milosevic would be public.
''You dragged the Serb people into war," Babic said. ''You brought shame on the Serbs."
Last month Babic testified against Milan Martic, the last president of Serb Krajina before the Croatian army recaptured the territory in 1995.
Asked on Feb. 15 to repeat his 2004 apology to the Croatian people, Babic said: ''I stand before this tribunal with a deep sense of shame and remorse. I allowed myself to participate in the persecution of the worst kind against people only because they were Croats, not Serbs," he said.