Europeanism and modernity...without whom one could not understand modern Spain". The Spanish public also gave a broadly positive opinion not only of the abdication but of his reign as a whole. According to a poll taken by El Mundo, 65% saw the King's reign as either good or very good, up from 41.3%. Overall, 55.7% of those polled in the 3–5 June survey by Sigma Dos supported the institution of the monarchy in Spain, up from 49.9% when the same question was posed six months prior. 57.5% believed the Prince could restore the royal family's lost prestige. An overwhelming majority of Spaniards believed the new King, Felipe VI, would make a good monarch and more than three-quarters believed King Juan Carlos had been right to hand over the throne to his son. Retirement Juan Carlos continued to have a role as institutional representative. In December 2015, Juan Carlos attended the inauguration of Mauricio Macri as President of Argentina as top Spanish representative. He announced by a letter to his son Felipe that his intention to retire from public life on 2 June 2019. In June 2019, the former King announced his retirement from official duties. Corruption investigations 2020 Saudi rail deal Recordings of the former King's alleged mistress Corinna zu Sayn-Wittgenstein-Sayn speaking with a former police chief were leaked to the press in mid-2018. Sayn-Wittgenstein claimed that Juan Carlos received kick-backs from commercial contracts in the Gulf States – particularly in the late-2000s construction of the €6.7 billion Haramain high-speed railway in Saudi Arabia – and maintained these proceeds in a bank account in Switzerland. She alleged that he purchased properties in Monaco under her name to circumvent the tax treatment of lawful residents, stating "[not] because he [loved] me a lot, but because I reside in Monaco." She further claimed the head of the Spanish intelligence service warned her that her life, and those of her children, would be at risk if she spoke of their association. The allegations drew demands for Juan Carlos to be investigated for corruption in early June 2019. Swiss authorities began investigating Juan Carlos in March 2020 in relation to a $100 million gift to Sayn-Wittgenstein in 2012. This donation was linked to alleged kick-back fees from Saudi Arabia. Sayn-Wittgenstein reportedly told the head Swiss prosecutor on 19 December 2018 that Juan Carlos had given her €65 million out of "gratitude and love", to