Saudi Crown Prince Nayef bin Abdulaziz al Saud - next in line to the nation's King Abdullah - has died.
A veteran Interior Minister in the kingdom, Prince Nayef was last October aged 78 when he was named crown prince and heir apparent to the Saudi throne.
A statement by the royal family released to Saudi state TV on Saturday said he died in Geneva, where he had been since May for medical tests.
Prince Nayef was known as a hardline conservative who was deeply distrustful of the nation's Shia religious faction, the BBC reported.
When he became Saudi Arabia's new crown prince, Prince Nayef had been the kingdom's interior minister for more than 35 years, the BBC reported in October last year. He was member of the influential 'Sudairi Seven', and the full brother of the late Crown Prince Sultan.
Prince Nayef was a likely choice for the role, having been appointed as second deputy prime minister in 2009, and in October 2011 became the key contender to be King Abdullah's successor to the Saudi throne.
Prince Nayef's appointment as crown prince posed many questions for Saudi Arabia's future, as he was regarded as being more socially conservative and less reform-minded than King Abdullah, the BBC reported.
Prince Nayef was one of seven sons born to former King Abdulaziz and Hassa bint-Ahmad al-Sudairi, who became known as the 'Sudairi Seven'. Hassa was said to be the former king's favourite wife, and the sons are now considered to be some of the most powerful figures in the kingdom, although only five of them are still alive.
Several of Prince Nayef's close relatives also hold senior government posts; his younger brother, Prince Salman, is the governor of Riyadh region. His son, Mohammad, is Saudi Arabia's counter terrorism chief and was once targeted by an al-Qaeda suicide bomber, but escaped with only minor injuries.
Prince Nayef was born in 1934 and was educated at the Princes' School in Riyadh, a specialist school created for the House of Saud's children, and by senior religious scholars.
Having studied diplomacy and security affairs, Prince Nayef took up his first government role at just 18 years of age, as deputy governor of Riyadh region. A year later he was promoted to become governor of the region.
In 1970 Prince Nayef began working at the Saudi Ministry of the Interior and by 1975 he was interior minister in the Saudi cabinet, a post he has held continuously ever since.
King Abdullah appointed him as Saudi Arabia's second deputy prime minister in 2009. The King's decision was driven by the fact that he was due to attend the G20 summit in London, and the first deputy prime minister, then-Crown Prince Sultan, was in America recovering from surgery.
He gained more responsibility in October 2010 after King Abdullah suffered a herniated disc in his back, forcing him to rest, and asked Prince Nayef to oversee the annual Hajj pilgrimage, in which over a million foreign Muslims travel to Mecca.
Although considered more conservative than King Abdullah, Prince Nayef has shown progressive tendencies in the past.
In 2001 Prince Nayef publicly supported a move to issue women with their own identity cards, a decision which gave women more freedom in many financial and legal transactions. Before the change was made women could only be registered on their fathers' or husband's cards.
However, he adopted a hardline tone in response to recent protests in Saudi Arabia prompted by the Arab Spring.
At a meeting of the Gulf Cooperation Council in March 2011 he said there were "evil people", who "wanted to make the kingdom a place for chaos and marches that are void of noble goals".