They embalmed the previous pope. After 33 (numerology buffs take note) days of being Pope, John Paul I ate too much of his medz. Oops.

Gennari: "John Paul II’s predecessor mistakenly took an overdose of tranquillisers... After his conversation with Cardinal Villot, the Pope mistook the dose he should have taken." (Ouest-France, undated press clipping, July 1984)

Cardinal Villot: "What occurred was a tragic accident. The Pope had unwittingly taken an overdose of his medicine. If an autopsy was performed it would obviously show this fatal overdose. No one would believe that His Holiness had taken it accidentally. Some would allege suicide, others murder. It was agreed that there would be no autopsy."