Bhumibol ascended the throne following the death by gunshot wound of his brother, King Ananda Mahidol, on 9 June 1946, under circumstances that remain unclear. While a first government statement declared that Ananda had accidentally shot himself,[21] an investigation committee ruled that this was impossible.[22] Two palace aides were convicted of regicide and executed. A third feasible explanation, that Bhumibol accidentally shot his brother while the boys played with their guns, was never seriously considered, as such an implication could have strongly damaged the institution of monarchy.[23] Bhumibol succeeded his brother, but returned to Switzerland before the end of the 100-days mourning period. Despite his interest in science and technology, he changed the subject and enrolled in law and political science to prepare for his duties as head of state. His uncle, Rangsit, Prince of Chainat, was appointed Prince Regent. In Bhumibol's name, Prince Rangsit authorized a military coup that overthrew the government of Thamrongnawasawat in November 1947.[24] He also signed the 1949 constitution, which gave back to the monarchy many of its powers that had been taken away by the 1932 Revolution.[25]