Callamard, who travelled to Turkey with a team that included a serious-crime investigator and a forensics expert, said she found that Saudi Arabia was hindering and undermining Turkish authorities' efforts to elucidate the circumstances of the journalist's death.
Ms. Callamard is due to submits her final report in June to the UN Human Rights Council, including recommendations on formal criminal accountability.
Saudi Deputy Public Prosecutor Shalaan bin Rajih Shalaan said investigators had concluded an intelligence officer ordered Khashoggi's murder, applying a lethal injection inside the consulate.
"The murder of Jamal Khashoggi and the sheer brutality of it has brought irreversible tragedy to his loved ones".
"It is also raising a number of global implications which demand the urgent attention of the worldwide community including the United Nations".
Later that year, Prince Mohammed ordered hundreds of influential businessmen and Saudi royals, some who had been considered contenders to the throne, locked up at the Ritz Carlton hotel in Riyadh, the Saudi capital, where they were interrogated.
Raptors to acquire Marc Gasol, send Jonas Valanciunas to Grizzlies
What I feel inside and how I feel about Memphis and its people has nothing to do with the franchise or a temporary thing. Ujiri added that he's already spoken to some agents regarding buyout candidates, via The Athletic's Eric Koreen .
Riyadh denies the Crown Prince had any involvement in the murder.
After denying Khashoggi was killed in the consulate for several weeks, Saudi Arabia indicted 11 people in the killing and is seeking the death penalty against five of them.
She said that Saudi killers had exploited diplomatic immunity to carry out the murder.
Unhappy with Riyadh's cooperation in the investigation, Ankara has called for an global inquiry.
Predicting little movement, a bipartisan group of senators on Thursday proposed a bill to cut off some weapons sales to Saudi Arabia including of tanks, long-range fighter jets and ordnance for automatic weapons.
Neither the Saudi government communications office nor Turkey's foreign ministry gave immediate responses to requests for comment on the report.
Citing a confidential report prepared for the Saudi public prosecutor by private U.S. security firm Kroll, the Wall Street Journal (WSJ) previously reported that none of the WhatsApp messages exchanged between MBS and Qahtani on the day Khashoggi was killed concerned the journalist or his murder.
Central Intelligence Agency officials had determined in November that Mohammed likely ordered the journalist's assassination, based on "an understanding of how Saudi Arabia works".