"There's not a smoking gun, there's a smoking saw", Graham said, in an apparent reference to reports that the columnist was beheaded, dismembered and his fingers were severed. "I have zero question in my mind", said the lawmaker.
Haspel provided the closed briefing just days before the Senate is expected to begin debating a resolution to withdraw USA support for the Saudi military campaign in Yemen.
Later Tuesday, Senate Democratic Leader Chuck Schumer issued a statement saying the briefing only "reinforced the need for a strong response to the murder of Jamal Khashoggi", and that Haspel "should brief the full Senate without delay".
"I think the reason they don't draw the conclusion that he's complicit, is because the administration doesn't want to go down that road, not because there's not evidence to suggest he's complicit", he said. John McCain, who has been on board with much of President Donald Trump's agenda since McCain's death in August, Graham has sided with critics of Trump's Saudi Arabia policy over the Khashoggi incident.
Graham said that you'd have to be "willfully blind" to not know Mohammed was responsible - a clear rebuke of Trump's argument that this whole thing resides in some kind of grey area.
The Saudis have charged 11 people but deny the crown prince was involved.
The United States now provides arms shipments and logistical support including intelligence and targeting assistance to the Saudi-led coalition, which includes the United Arab Emirates and other Arab countries. The Senate voted last week to debate the US assistance, and additional Senate action is expected in the coming days.
Bin Salman has denied any knowledge of the plot to torture, murder and dismember Khashoggi at the Saudi Consulate in Turkey in October and the USA has waffled on whether it believes his denials.
"It's not in our interests to give the crown prince. a pass for murder of an American resident with three American children", Graham said.
RICARDO MAZALAN APSaudi Arabia's Crown Prince Mohammed bin Salman was shunned by some leaders at the G20 summit
Last week's vote set up debate on Senate passage of the Yemen resolution, which could happen next week.
Members of that chamber are scheduled to receive a briefing from Defense Secretary Jim Mattis and Secretary of State Michael Pompeo on December 13, according to a House aide.
Senators, however, were divided as to what steps to take next, following a stinging vote last week to consider a measure cutting off USA military aid to Saudi Arabia's campaign.
USA intelligence officials reportedly have concluded that the crown prince, known informally as "MBS", must have at least known of the plot.
The president has touted Saudi arms deals worth billions of dollars to the USA and recently thanked Saudi Arabia for plunging oil prices.
"All evidence points to that all this leads back to the crown prince", said, Alaska Republican Senator Richard Shelby, calling the murder a "reprehensible conduct".
"The worldwide community seems to doubt Saudi Arabia's commitment to prosecute this heinous crime".
But Graham said he would not support the joint resolution that would cut off military support to the Saudi-led coalition in Yemen.