The journalist had made a decision to leave his native Saudi Arabia for the U.S. in September 2017, but was lured to the embassy in Istanbul on in October 2018 to collect papers for his upcoming marriage.
Special UN rapporteur, Agnes Callamard, said Thursday after a visit to Turkey that the killing of Khashoggi, who had written critical pieces on Saudi Arabia in The Washington Post, had been "planned and perpetrated" by Saudi officials.
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.
Photo by Depo Photos/ABACAPRESS.COM.
Trump has faced increasing pressure at home by members of both parties to take a more forceful stance with Crown Prince Mohammed bin Salman.
She did not point to any specific official.
He was visiting the consulate to obtain paperwork for his upcoming marriage to a Turkish woman.
Ms Callamard is due to submit her final report in June to the UN Human Rights Council, including recommendations on formal criminal accountability.
Saudi authorities have since charged 11 people with Khashoggi's murder.
"It is also raising a number of worldwide implications which demand the urgent attention of the global community, including the United Nations".
Agnes Callamard, UN special rapporteur on executions, sought access to the Saudi consulate in Istanbul.
While the murder took place on 2 October, authorities only got access to the consulate on 15 October, and not to the residence there until 17 October - which in particular affected the forensic investigation, she wrote.
Ms Callamard was reporting on a week-long mission with her team of three experts to Turkey.
Turkish President Recep Tayyip Erdogan on Sunday accused the United States of maintaining "silence" on the murder, which has strained the kingdom's ties with Washington. "We want everything to be clarified because there is an atrocity, there is a murder", Erdogan told an interview with state-run TRT television.
"The murder of Jamal Khashoggi and the sheer brutality of it has brought irreversible tragedy to his loved ones", said Callamard.
Human rights groups and other observers also say the Saudi investigation into the killing has not met global standards and they have called for a thorough probe into the slaying. It reportedly read that prior to his conversation with Aldakhil, the Saudi crown prince had complained to his other adviser, Saud Qahtani, about Khashoggi's growing influence as his materials were undermining the prince's image of a reformer.
The prosecutor said earlier this month his office was seeking the death penalty for five of the 11 indicted suspects.