PARIS, March 12 -- Former Yugoslav president Slobodan Milosevic died of a heart attack, according to autopsy results released Sunday by the U.N. war crimes tribunal in The Hague. A more detailed examination to determine the cause of the heart failure is pending, the court said.

Milosevic, 64, the first former leader of a state to be tried for genocide and other crimes against humanity, was found dead Saturday on his bed in his cell at the U.N. tribunal's prison outside The Hague. Milosevic had been on trial for the past four years for his role in four Balkan wars during the breakup of Yugoslavia in the 1990s. The trial had been expected to conclude by May.

Sunday night's announcement came at the end of a day of speculation about his death that had taken on the drama of a mystery novel. The war tribunal's chief prosecutor, Carla Del Ponte, said at a news conference that suicide was a "possibility."

A short time later, one of Milosevic's attorneys showed reporters two letters purportedly written by Milosevic on Friday that claimed he was being poisoned with drugs that were neutralizing his medication for high blood pressure and a chronic heart condition.

"According to the pathologists, Slobodan Milosevic's cause of death was a 'myocardial infarction,' " the medical terminology for a heart attack, the international war crimes tribunal said in a statement, adding, "The pathologists identified two heart conditions that Slobodan Milosevic suffered from, which they said would explain" the heart attack.

The autopsy was performed by Dutch forensic pathologists in The Hague, under the observation of two pathologists from Belgrade at the request of the government of Serbia and Montenegro, the tribunal said in a statement.

The tribunal said that a toxicological exam to determine the cause of the heart attack "will still be carried out" and that "the final report will be issued as soon as possible."

Zdenko Tomanovic, a lawyer who has been helping Milosevic prepare his defense before the war crimes tribunal, told reporters in The Hague on Sunday that Milosevic had written a letter to the Russian Embassy there and to the Russian foreign minister last Friday saying: "They would like to poison me. I'm seriously concerned and worried."

Milosevic based his allegations on a Jan. 12 medical report showing "strong drugs in his system only used for treating leprosy or tuberculosis," Tomanovic said. He said the drugs were countering the effects of the medicine prescribed for Milosevic's high blood pressure and heart condition.

Milosevic last month had asked the court to allow him to travel to Moscow for medical treatment. The judges rejected the request, saying he could bring his own doctors to the prison. They also said they feared he would not return to The Hague.

"In the letter, Milosevic stressed that the main reason that he was not allowed to go to Moscow for medical treatment was the existing fear by some that the careful examination by the Russian hospital would reveal that his health was being systematically destroyed," Tomanovic said. "Milosevic pointed out that during the last five years he had never used any such antibiotics, especially since he never had leprosy or tuberculosis or any kind of infectious disease except for the flu."

Milosevic's death distressed court officials, who have concentrated much of the court's time and resources on the trial against their highest-profile defendant.

"It is extremely unfortunate that the victims and their families will not have a final answer in this case on the criminal responsibility of the accused," the tribunal's president, Fausto Pocar, said at a news conference Sunday at the court in The Hague.

The tribunal said Milosevic's body would be given Monday to his family, which reportedly is bickering over funeral and burial arrangements.

The Russian news agency Interfax reported that Mirjana Markovic, Milosevic's widow, and their son, Marko, want him buried in Moscow, where they live in exile in a bid to avoid criminal charges in Serbia. Markovic was a key adviser to her husband, and prosecutors have been considering charging her with incitement to murder for assassinations carried out under Milosevic's rule.

Milosevic's daughter, Marija, told Belgrade's Beta news agency that she wanted her father buried in Serbia, where he was born.

"He is not Russian," she said from her home in Montenegro, the last republic of the former Yugoslavia still linked to Serbia. Marija is wanted in Serbia for allegedly firing a gun at police who arrested Milosevic before his extradition to The Hague.

The Socialist Party also wants a funeral for Milosevic in Belgrade and to bury him in a section of the city's main cemetery reserved for national leaders and heroes.

"It should be a huge political demonstration in support of his policies," said Ivica Dacic, the party's leader.

In Belgrade on Sunday, disparate commemorations underscored the deep conflicts of Serbian politics and the public's divided emotions over a man some hail as hero and others condemn as the "Butcher of the Balkans."

A stream of mourners paid condolences at the headquarters of the Socialist Party of Serbia, which Milosevic founded. They lit candles, signed a visitors' book and placed flowers near a photo of Milosevic.

Marina Petrovic, shedding tears, carried a book by Milosevic titled "I Accuse," an account of his opening speech at The Hague, illustrated by pictures of Serb civilians killed in the various Balkan wars. "He suffered, and so did we," she said. "The world will regret the way it treated him."

The red, white and black Serbian flag flew at half-staff over the Socialist Party headquarters, but not at public buildings elsewhere in the city. The government of Serbian President Boris Tadic has declined to declare an official period of mourning. Small, impromptu memorial gatherings were reported in Pozarevac, Milosevic's birthplace, and in Serb-populated towns in Bosnia.

At Belgrade's Novo Groblje cemetery, hundreds of mourners commemorated the third anniversary of the assassination of Zoran Djindjic, an enemy of Milosevic who was prime minister when a sniper killed him. Djindjic spearheaded an opposition movement that led to Milosevic's ouster in 2000. The next year, he arranged Milosevic's transfer to The Hague to stand trial for war crimes. Tadic attended the memorial at Djindjic's granite-covered grave and lit a candle.

Correspondent Peter Finn in Moscow and special correspondent Rade Maroevic in Belgrade contributed to this report.