Saudi Crown Prince Mohammed bin Salman sent at least 11 messages to his closest adviser, who allegedly oversaw the team that killed US columnist Jamal Khashoggi, in the hours before and after his death in October, The Wall Street Journal reported on Saturday, citing a highly classified CIA assessment report.

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The killing of Khashoggi, a US resident who wrote for The Washington Post, has emerged as the most serious threat to American-Saudi ties since the September 11, 2001, terror attacks. US senators have demanded the White House be more forthcoming about intelligence gathered on Khashoggi’s killing in Turkey, and demanded to know whether the crown prince knew about in advance or ordered it.

The Wall Street Journal said it had reviewed excerpts of the Central Intelligence Agency’s assessment, which included electronic intercepts and other information.

The excerpts state that the CIA had “medium-to-high” confidence that Prince Mohammad had personally targeted Khashoggi to the extent of “probably ordering his death”. However, the assessment stated there was no direct reporting of the crown prince actually issuing a kill order, The Wall Street Journal said.

Prince Mohammed had sent the electronic messages to Saud al-Qahtani, who supervised the 15-man team that killed Khashoggi and was in direct communication with the team’s leader in Istanbul, the Journal said, citing the CIA report. The content of the messages between Prince Mohammed and Qahtani isn’t known.

The report is one of several in which the US intelligence community has concluded with high confidence that Prince Mohammed ordered the killing. American officials, including Trump, have publicly questioned whether the crown prince’s role will ever truly be known.