But which one? It's Prince Turki bin Faisal bin Turki bin Abdulaziz Al Saud. But there are two people with that name. There's the elder Prince Turki, brother of Crown Prince Sultan and one of the Sudairi Seven. But there's also the younger Prince Turki (the elder's son?) and going by age given for the deceased in this report from Qatar, it might be him. An untimely death for him would be grist for the mill on the 9/11 conspiracy theories. He had also been recently in the lead on expressing Saudi frustration with the Israel-Palestine peace (sic) process (sic), and had never been a fan of the neocons, for which the feeling was mutual.
UPDATE April 4: The younger Prince Turki (al-Faisal) has popped up on a visit to Jordan so it's not him.