Dutch prosecutors concluded Wednesday that former Yugoslav President Slobodan Milosevic died of a heart attack and was not killed while in U.N. custody, countering allegations by his family that he was slain.

Milosevic, who was 64 and had a history of heart problems, was found dead in his cell on March 11, prompting allegations from his family and supporters that he had been poisoned or had died as a result of neglect by his U.N.-appointed doctors.

The former Yugoslav leader had been on trial in The Hague, Netherlands, for genocide and crimes against humanity

"The district attorney concluded that Mr. Milosevic died of natural causes and there is no indication that his death was the result of a crime," prosecutors said in a statement.

Judge Fausto Pocar, the president of the U.N. Yugoslav war crimes tribunal, welcomed the final report that formally closed the Dutch investigation. But the tribunal will continue investigating the medical treatment Milosevic received in detention, Pocar said.

"The internal inquiry expects to conclude its investigation on these issues shortly," he said.

Prosecutors said Milosevic was believed to have died between 7 and 9 a.m. that morning, probably around 7:45 a.m..

They said guards knocked on his door for a 9 a.m. wake-up, but assumed he was still sleeping and left him alone until 10 a.m. when they found his lifeless body in his bed.

A Dutch doctor was summoned and confirmed the death a half hour later, said the statement from the district attorney.

The medical reports on Milosevic's death have been released piecemeal, with the first report citing a heart attack as the cause of death and a second toxicological report ruling out poison or an overdose of medication.

"In line with earlier preliminary findings, the National Forensic Institute can now definitely conclude that the cause of death was a heart attack. The autopsy uncovered serious heart defects which resulted in the heart attack," prosecutors said.

The tribunal has asked Sweden to investigate the running of the detention center, following allegations that Milosevic had access to alcohol and unapproved medicines.

Milosevic was approaching the final months of a four-year-long trial on 66 counts of genocide and crimes against humanity. The case had been repeatedly interrupted because of his poor health and high blood pressure worsened by the stress of conducting his own defense.

Prosecutors said the tribunal reported that medical tests early this year showed Milosevic was taking non-prescribed medicine, including Rifampicine, a powerful antibiotic that could have undermined his regime of heart medication prescribed by the detention center's own doctors.

"That is why the public prosecutor ordered a toxicological report and Milosevic's cell was searched," prosecutors said. But the search, conducted the day after his death, found "no drugs other than his prescribed medication or other contraband."