The fiancée of missing Saudi journalist Jamal Khashoggi has asked President Donald Trump to help uncover what happened to the Riyadh critic who she said had "been fighting for his principles".
Hatice Cengiz made the appeal in an opinion piece for The Washington Post newspaper, where Khashoggi was a columnist and an outspoken critic of some of Riyadh's policies.
A veteran journalist, Khashoggi disappeared on October 2 after entering Saudi Arabia's consulate in Istanbul to arrange paperwork for his wedding to Cengiz, a Turk.
Government sources in Turkey said police believe the 59-year-old was killed inside the consulate, claims which Riyadh dismissed as "baseless".
Cengiz wrote that she was "confident in the abilities of Turkish government officials."
"At this time, I implore President Trump and First Lady Melania Trump to help shed light on Jamal's disappearance," she said.
"I also urge Saudi Arabia, especially King Salman and Crown Prince Mohammed bin Salman, to show the same level of sensitivity and release CCTV footage from the consulate," Cengiz wrote.
Trump on Monday expressed concern about Khashoggi's case and Secretary of State Mike Pompeo called for a thorough investigation.
Turkish police were also looking into the possibility that Khashoggi was kidnapped, local media reported.
Riyadh has said Khashoggi left the consulate after his visit.
Although Khashoggi knew that his opinions had angered certain people, he entered the consulate "without doubting he would be safe there," his fiancee wrote, but after three hours of waiting "fear and concern" overcame her.
Khashoggi had fled his homeland in September last year and had been living in self-imposed exile in the United States, where he had applied for US citizenship, Cengiz said.
A former Saudi government advisor, Khashoggi has been openly critical of Prince Mohammed, accusing him of introducing a new era of "fear, intimidation, arrests and public shaming."
Cengiz wrote she remains confident that the "great man" is still alive, "although my hope slowly fades away each passing day."