Saudi Arabia’s Crown Prince Nayef bin Abdulaziz al-Saud has died in Geneva, Saudi state television announced on Saturday, citing a royal court statement.

The royal court issued today the following statement: “With deep sorrow and grief, the Custodian of the Two Holy Mosques, King Abdullah Bin Abdulaziz Al Saud, announced the death of his brother, Crown Prince Nayef Bin Abdulaziz Al Saud, Deputy Premier and Minister of Interior, who passed away on Saturday, Saudi gazette reported.

Prince Nayef, who served as Interior Minister since 1975 and led a crackdown on Al-Qaeda in the Kingdom stop their wave of bloody attacks on the kingdom between 2003 and 2006, was the heir to Saudi King Abdullah and was appointed crown prince in October 2011 after the death of his elder brother, Crown Prince Sultan. Prince Nayef had been in Switzerland since May for medical tests while details about his illness haven’t been made public.

Unlike in European monarchies, the line of succession in Saudi Arabia does not move directly from father to eldest son but moves down a line of brothers born to the kingdom’s founder Ibn Saud. King Abdullah said the prince would be buried after sunset prayers on Sunday in the Muslim holy city of Mecca, according to a Saturday statement.

Nayef’s death unexpectedly reopens the subject of succession in this crucial US ally and oil powerhouse for the second time in less than a year, according to Al Jazeera. 

The 88-year-old Abdullah has now outlived two appointed successors, despite health risks of his own. Now, a new crown prince must be appointed from among his brothers and half-brothers, all the sons of Saudi Arabia’s founder, Abdul-Aziz.