Saudi Arabia's powerful interior minister Prince Nayef bin Abdul Aziz, who on Thursday was named crown prince after the death of his brother Sultan, led an iron fist crackdown on Al-Qaeda.
Prince Nayef, 78, seen as more conservative than his half brother King Abdullah, 87, is a pragmatist who likes to describe himself as a soldier under the command of the Saudi monarch.
But like the former Crown Prince Sultan who died Saturday, Nayef also has health problems. According to experts on the Saudi monarchy, Nayef was treated abroad in April for cancer.
The new crown prince is also known for his solid relations with the kingdom's religous elite and is believed to oppose reforms that could liberalize this ultra-conservative Islamic society.
He is known for his suspicion and mistrust of Saudi Arabia's arch-rival Iran, and has pushed for hardline policies towards the Shiite nation.
Interior minister for more than three decades, Nayef enjoys strong relations across the Arab region.
Diplomats say he played a key role in the kingdom's decisions to host Tunisia's ousted strongman Zine El Abidine Ben Ali in January, and to dispatch troops in March to Bahrain to help end protests led by the Shiites.
Born in the western city of Taif in 1933, Nayef was quickly pushed into public service, being named governor of Riyadh when he was barely 20.
His elder brother Fahd brought him into the interior ministry, where he was named deputy minister in 1970 and minister five years later, when Fahd became crown prince.
Nayef was credited for the successful crackdown on Al-Qaeda militants in subsequent years, halting their wave of bloody attacks on the kingdom between 2003 and 2006.
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His internal security campaign forced Al-Qaeda leaders and many members to flee to southern neighbour Yemen, where they formed Al-Qaeda in the Arabian Peninsula, which continues to threaten Saudi interests.
Charged with managing the country's borders, its internal crime-fighting apparatus and the internal intelligence force, the mabahith, he dismantled charities which used to collect donations for Osama bin Laden and his network.
Nayef's son, Prince Mohammed, who is the assistant interior minister and the kingdom's top counter terrorism official, escaped assassination in 2009, when a suicide bomber from Yemen tried to kill him.
In recent years he has handed over the day-to-day security responsibilities to Mohammed, who has been even more methodical in pursuing Islamist radicals and battling their ideology.
But critics have accused Prince Nayef of targeting democracy and human rights activists while neglecting, until recent years, the rise of Islamic radicalism in the country.
Saudis however have shown support and appreciation for the strongman persona that Nayef reflects due to public perceptions that he can deliver on national security.
Nayef told reporters early in 2009 that he opposed electing members of the consultative Shura council, or to include women in the group. "I don't see the need for that," he said.
He defended members of Saudi Arabia's religious police, who have often been accused of brutality and abuse.
In recent months, the interior ministry has played a key role in preventing popular demonstrations. Prince Nayef has publicly thanked Saudis for not answering local activists' calls for protests.
The ministry has also sought to maintain order in the face of increasing unrest in the primarily Shiite inhabited and oil-rich Eastern province, where the kingdom accuses Iran of inciting the local population against the Sunni-led monarchy.
Nayef is the middle prince of the Sudairi Seven, the formidable bloc of sons of King Abdul Aziz by a favourite wife, Princess Hassa al-Sudairi.
Among his other full brothers are King Fahd, who died in 2005, Crown Prince Sultan who passed away on Saturday and Prince Salman, governor of Riyadh.