CIA Director Gina Haspel is expected to brief leaders of multiple Senate committees Tuesday about the October murder of Saudi activist and writer Jamal Khashoggi, a source told Fox News.

The source said the briefing will include leaders of the Senate Foreign Relations Committee, Armed Services Committee and Appropriations Committee.

Haspel did not attend a briefing about Khashoggi's killing that was given to all senators last week by Defense Secretary James Mattis and Secretary of State Mike Pompeo. Her absence upset lawmakers on both sides of the aisle, with Sen. Lindsey Graham, R-S.C., vowing to hold up Congress' agenda for the current lame-duck session until he heard from the CIA director.

""I'm not going to be denied the ability to be briefed by the CIA," said Graham, who added: "The question for me is whether or not the CIA supports the conclusion with a high degree of confidence that the[Saudi] crown prince [Mohammed bin Salman} was complicit in the murder of Mr. Khashoggi."

U.S. intelligence officials have concluded that the crown prince, known informally as "MBS," must have at least known of the plot. However, the CIA's findings have not been made public and President Trump has equivocated over who was to blame. Following the Nov. 28 briefing, Pompeo and Mattis told reporters there was no direct evidence tying MBS to Khashoggi's murder.

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Sen Bob Menendez, D-N.J., the ranking member of the Senate Foreign Relations Committee, speculated that Haspel didn't attend the briefing because she "would have said with a high degree of confidence that the crown prince of Saudi Arabia was involved in the murder of Jamal Khashoggi."

At the time, a CIA spokesman denied that Haspel was told to stay away from the briefing.

Khashoggi was killed Oct. 2 in what U.S. officials have described as an elaborate plot at the Saudi Consulate in Istanbul, which he had visited for marriage paperwork.

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Trump has said it may never be known who was responsible for the killing, and in public comments — and a long and unusual statement last week — he reinforced the United States' long alliance with the Saudis.

The Associated Press contributed to this report.