Slobodan Milosevic died of a heart attack in his jail cell, a nearly eight-hour autopsy on the former Yugoslav president revealed, the UN war crimes tribunal said. The tribunal released a statement Sunday saying it had received "a brief summary of the autopsy results. According to the pathologists, Slobodan Milosevic's cause of death was a 'myocardial infarction'" - a heart attack. The statement came after a day of speculation on the cause of death that swirled from ill health to suicide to poison. Tribunal spokeswoman Alexandra Milenov said the autopsy revealed Milosevic had been suffering from two heart conditions. She did not name the conditions, but said the doctors determined they might have caused the heart attack. She also said toxicological tests were still to be carried out. Asked if poisoning could have caused the heart attack, Milenov said it was too early to draw conclusions. Slobodan Milosevic wrote a six-page letter the day before he was found dead, claiming that traces of a "heavy drug" had been found in his blood and that he feared being poisoned, a legal aide to the former Yugoslav president said Sunday. Milosevic was "seriously concerned" about being poisoned, Tomanovic said. Milosevic had appealed to the war crimes tribunal last December to be allowed to go to a heart clinic in Moscow for treatment. The request was denied. He repeated the request as late as last month. Milosevic underwent frequent medical examinations by doctors and specialists appointed by the tribunal and by Serb doctors brought at his own request. Detailed reports were routinely submitted to the judges. The letter alleged that a powerful drug used to treat leprosy or tuberculosis had been found in his blood during an examination last January 12, Tomanovic said. "They would like to poison me," the lawyer quoted Milosevic as telling him. Reading a sentence from an English translation of the letter, Tomanovic said: "In any case, the persons who are giving me the drug for the treatment of leprosy surely cannot be treating me, and especially those persons from whom I defended my country in the war and who also have an interest in silencing me." The Belgrade lawyer described the drug as an antibiotic, but said he couldn't remember the name. Milosevic had never knowingly taken such a drug, Tomanovic claimed. Tomanovic said he saw the jailed Serb leader on Friday at 4:30 p.m. His body was found the next morning, and by 11 a.m. the letter was delivered to the Russian Embassy.