The probe found that Milosevic, who had long suffered from high blood pressure and related heart problems, "died a natural death and that there are no indications that the death resulted from crime," the prosecutor's office said in a statement.
"During the autopsy serious heart diseases were diagnosed which have caused the cardiac arrest. There were no signs of external violence," the probe found.
The statement also said no non-prescribed medicines were found in the former Yugoslav leader's body, including rifampicin, a strong antibiotic that would have countered the effects of his heart medication.
"In conformance with ... preliminary findings, the NFI (Netherlands Forensic Institute) has now definitely come to the conclusion that the cause of death was cardiac arrest," the statement said, giving the time of death as between 7am and 9am on March 11.
Milosevic was found dead around 10am that morning in his cell at the UN war crimes tribunal based in The Hague, where he was being tried over his role in the 1990s wars that broke up the old Yugoslav federation. He was 64.
According to the Dutch prosecutor's office the guards had already tried to wake Milosevic an hour earlier that day.
"They assumed that he did not react to the wake-up call because he was asleep and only entered his cell at 10 am," the statement said.
The four-year trial of the former Yugoslav strongman, who faced 66 counts including genocide over the 1995 Srebrenica massacre, was expected to wrap up this year.
Milosevic's supporters in Russia, where his widow lives, and in his native Serbia have alleged he was poisoned, while the International Criminal Tribunal for the Former Yugoslavia (ICTY) suspected he was taking rifampicin to make his health deteriorate so he would be allowed to seek treatment in Moscow.
The statement from the Dutch prosecutor's office said: "No indications were found that showed poisoning, and neither were toxicological factors found that might have provoked a cardiac arrest".
"A number of the medicines prescribed to Mr Milosevic were found in the body material, however not in toxic concentrations. No traces were found of medicines that had not been prescribed."
"The NFI furthermore has concluded that it is not likely that rifampicin had been taken or administered several days prior to the decease," it said.