Khashoggi, who was killed in the Saudi consulate in Istanbul last month, was reportedly given assurances that it was safe for him to attend the consulate in a phone call with the Saudi ambassador to the US, Khalid bin Salman, who is the brother of the Crown Prince.
The Washington Post reported on Friday night that the US intelligence agency intercepted a call from the Crown Prince to his brother Khalid in which he instructed him to telephone Khashoggi.
It is not clear if Khalid bin Salman knew that Khashoggi would be killed, but it is the clearest evidence yet that the order to murder the journalist came from the very highest levels of the Saudi government.
Saudi Arabia has repeatedly denied that the Crown Prince had any involvement in the death of Khashoggi, who had been a fierce critic of Mohammed bin Salman.
The revelation will put further pressure on President Donald Trump to publicly rebuke Saudi Arabia's leaders over the diplomatic crisis. The White House has so far been reluctant to damage their relationship with a key ally and trading partner in the Middle East, with Mr Trump repeating Saudi claims that the murder was the result of rogue agents.
The Crown Prince, who is expected to become the next Saudi king, had been seen as a moderniser by Western allies. However international outcry over the murder of Mr Khashoggi has brought his involvement in the affair under heavy scrutiny.
Saudi Arabia has offered shifting explanations or the incident, most recently claiming that rogue operatives injected Khashoggi with a lethal drug overdose. The kingdom has announced charges against 11 people it says were involved and vowed to seek the death penalty against five. Some of the hit team have been identified as key aides to the Crown Prince and other senior Saudi officials.
The CIA reportedly obtained the intelligence that Khashoggi's life may have been in danger before his murder but it was not discovered until after his disappearance, intelligence sources told the Washington Post.
Khashoggi was not considered "a person of interest" before his disappearance, and was regarded as protected from American intelligence gathering in part because of his status as a US resident, according to the sources.
It was only after his death that US intelligence agencies began searching their archives and uncovered material suggesting the Saudi royal family had been attempting to lure the dissident back to the country.
Khalid bin Salman issued a vehement public denial of the reports, insisting that his last communication with the journalist was by text message in 2017.
As we told the Washington Post the last contact I had with Mr. Khashoggi was via text on Oct 26 2017. I never talked to him by phone and certainly never suggested he go to Turkey for any reason. I ask the US government to release any information regarding this claim.— Khalid bin Salman خالد بن سلمان (@kbsalsaud) November 16, 2018
"I never talked to him by phone and certainly never suggested he go to Turkey for any reason.
"I ask the US government to release any information regarding this claim," he added.