Haspel had faced mounting pressure to speak to lawmakers and more fully explain the CIA's findings, which President Donald Trump has said don't conclusively show that Mohammed was involved in the assassination.
Senators put themselves in direct opposition to the White House, making clear that the evidence they heard had convinced them beyond the shadow of a doubt.
"If the Crown Prince went in front of a jury, he would be convicted in 30 minutes," said Senator Bob Corker, R, the chairman of the Committee on Foreign Relations.
Haspel was noticeably absent last week from an all-senators briefing with Secretary of State Mike Pompeo and Defence Secretary Jim Mattis. Lawmakers complained that the Trump Administration was depriving Congress of key information about the killing of Khashoggi by refusing to order Haspel to go to the Hill and explain the CIA's assessment.
The CIA has concluded that Mohammed probably ordered the killing, based in part on intercepted communications involving him and a key aide, who is alleged to have overseen the team that killed the journalist inside the Saudi Consulate in Istanbul in October, according to people familiar with the matter.
The spy agency also analysed other intercepted communications, listened to audio provided by Turkey from inside the consulate, and assessed that an audacious operation that involved killing a Saudi citizen in a foreign country could not have been executed without the crown prince's knowledge, people familiar with the CIA's conclusions said.
Haspel provided the closed briefing just days before the Senate is expected to begin debating a resolution to withdraw US support for the Saudi military campaign in Yemen.
Graham, a confidant of Trump, had said he would refuse to support "any key vote" until Haspel spoke to lawmakers.
Some senators had accused the White House of barring Haspel's participation in last week's briefing with Pompeo and Mattis. But CIA spokesman Timothy Barrett said nobody told Haspel not to appear.
Haspel spoke only to Senate leaders and the heads of national security committees with an interest in Saudi policy regarding Yemen and the intelligence surrounding Khashoggi's killing, according to multiple people familiar with the plans.
Bipartisan leaders from the Foreign Relations Committee, the Armed Services Committee, the Intelligence Committee, and the Appropriations subcommittees that fund the State and Defense departments were expected to be included.
Some rank-and-file senators were furious that they were excluded from the briefing.
"I can't even ask to be included in it because I didn't know it was going to happen, except for reading about it in the media. That's not the way it should be. She should have come and testified in front of all senators," Sen. Rand Paul (R-Ky.) said. "If you have some senators who are more equal than others, that is not democratic representation."
Last week, the Senate took the historic step of voting to take up a resolution, spearheaded by Sens. Bernie Sanders (I-Vt.) and Mike Lee (R-Utah), to end U.S. support for the Saudi-led coalition fighting Houthi rebels in Yemen, where thousands of civilians have been killed and, according to the United Nations, millions are at risk of starvation.
For some of the 14 Republicans who supported the procedural step last week, the vote was intended as a warning shot to Trump, to inspire him to start openly condemning Mohammed or withholding military support from the Saudis.
Haspel's briefing may have been designed to placate some of those senators. But it is not expected to deter Senate Democrats — or the handful of Republicans who say Saudi Arabia should be rebuked — from supporting the Yemen resolution beyond its next step, a vote expected to take place in the next few days.
