The previous Prime Minister died in 1964: https://en.m.wikipedia.org/wiki/Hossein_Ala%27 https://en.m.wikipedia.org/wiki/Hossein_Ala%27 Mossadeq became Prime

The previous Prime Minister died in 1964: https://en.m.wikipedia.org/wiki/Hossein_Ala%27 https://en.m.wikipedia.org/wiki/Hossein_Ala%27 Mossadeq became Prime Minister in 1952. So he did not become Prime Minister by assassinating the previous guy. The predecessor of Mossadeq's predecessor was assassinated however: https://en.m.wikipedia.org/wiki/Haj_Ali_Razmara https://en.m.wikipedia.org/wiki/Haj_Ali_Razmara I have seen no evidence it was by Mossadeq. The assassin was a member of an extremist Islamic group, not Mossadeq's secular National Front. You are right as far as him being released during Mossadeq's administration but there are many possible explanations for his release other than Mossadeq playing a role in the assassination. There were many other factions and political movements at play at that time. As far as I know Mossadeq was not an especially violent man. He had the option of putting down the protests that led to his deposition but refused to give the order.