The C.I.A. has evidence that Mohammed bin Salman, the Saudi crown prince, communicated repeatedly with a key aide around the time that a team believed to have been under the aide’s command assassinated Jamal Khashoggi, according to former officials familiar with the intelligence.

The adviser, Saud al-Qahtani, topped the list of Saudis who were targeted by American sanctions last month over their suspected involvement in the killing of Mr. Khashoggi. American intelligence agencies have evidence that Prince Salman and Mr. Qahtani had 11 exchanges that roughly coincided with the hit team’s advance into the Saudi Consulate in Istanbul, where Mr. Khashoggi was murdered…

“This is the smoking gun, or at least the smoking phone call,” said Bruce Riedel, a former C.I.A. official now at the Brookings Institution. “There is only one thing they could possibly be talking about. This shows that the crown prince was witting of premeditated murder.”