The cause of Ayatollah Akbar Hashemi Rafsanjani’s death a year ago is proving to be as difficult to explain as his storied political career. On Jan. 7, Yasser Hashemi, one of Rafsanjani’s sons, said President Hassan Rouhani had rejected the findings of the Supreme National Security Council regarding the cause of Rafsanjani’s death and ordered the council to reopen the investigation.

This claim is not new, however. On Dec. 16, one of Rafsanjani’s daughters, Faezeh Hashemi, told an Iranian newspaper that the council had told her that Rafsanjani’s body had 10 times the permissible radioactivity. Rafsanjani's brother Mohammad Hashemi also said on the same day that no one has yet explained how his brother suffered from cardiac arrest. He reiterated these comments Jan. 7, saying the lack of answers is leading to doubts about Rafsanjani's death. All of these comments made headlines across Iranian media and led to speculation, once again, about the sudden end of one of the most influential political figures in modern Iran.

Sudden, unexplained deaths of political figures are not unheard of in Iran. Ali Shariati, one of the most well-known intellectuals and revolutionaries in Iran, died in 1977 at the age of 43 while in exile in the United Kingdom. Two of Ayatollah Ruhollah Khomeini’s sons died suddenly: Mostapha while in exile in Najaf in 1977 and Ahmad in 1995, six years after his father’s death. Lesser-known figures wrapped up in political scandals also have died suddenly. A doctor who testified about torture at one of Iran’s notorious prisons also wound up mysteriously dead in 2009, with officials claiming it was suicide.

The death of Rafsanjani, however, is perhaps more significant than all the cases cited above. Despite having lost a number of elections after having served twice as president in the 1990s, Rafsanjani was experiencing an uptick in popularity in the last decade. His support for the Iranian nuclear deal, better relations with the West and his antagonism toward the county’s hard-liners earned him a reputation as a wise, elder statesman who expressed the opinions of more liberal-minded Iranians seeking an end to the country’s isolation. With his support for Rouhani in 2013, Rafsanjani showed that he still had enough public influence, along with former President Mohammad Khatami, to sway presidential elections.