State-run Anadolu news agency said that the Turkish prosecutor's office had taken testimonies from 20 consulate employees, and that 25 more people including foreign nationals would be questioned as part of the investigation.
Saudi Arabia provided no evidence to support its account of the circumstances that led to Khashoggi's death and it was unclear whether Western allies would be satisfied with the Saudi version of events.
Saudi Arabia has confirmed the death of Washington Post columnist Jamal Khashoggi on Friday.
US Federal Reserve officials are monitoring the case of Khashoggi and the possibility that any sanctions against Saudi Arabia could disrupt oil markets, Atlanta Fed President Raphael Bostic said on Friday.
Khashoggi went missing more than two weeks ago after entering the consulate to obtain documents for his forthcoming marriage.
Saudi court officials reported that Khashoggi, who was being interrogated, died in a chokehold, according to CNN. The majority of the suspects included 15 Saudis who reportedly flew in from Riyadh the same day as Khashoggi's disappearance.
Sabah's report does not name the man in the CCTV image, but he has been previously identified as Maher Abdulaziz Mutreb, a reported bodyguard and regular member of Crown Prince Mohammed bin Salman's entourage.
The four organizations said an worldwide investigation should probe Saudi Arabia's role and aim to identify everyone responsible for ordering, planning and executing any operations related to Khashoggi's disappearance.
Security services in Turkey have used pro-government media to leak details of Mr Khashoggi's case, adding to the pressure on the kingdom.
On Thursday, after his meeting at the White House, Pompeo said that he told the president that the Saudis should have "a few more days" to finish their investigation into Khashoggi's disappearance.
News of Khashoggi's disappearance emerged after his fiancée, Hatice Cengiz, told friends she waited outside the consulate for almost 12 hours and didn't see him exit the building.
Earlier on Thursday, Pompeo said he told Trump that the U.S. should give the Saudis "a few more days" to complete their investigation into Khashoggi's case "so we can get a complete understanding" of the facts.
He said he did not believe the prince would have acted in the way he did unless he believed he had been given "licence" to do so by the USA administration of Donald Trump. "That's based on everything - intelligence coming from every side".
But the story does not acknowledge that Trump has promised "severe consequences" if it is found Saudi intelligence agents killed Khashoggi in the embassy, as the government of Turkey has charged. "We'll certainly consider a wide range of potential responses, but I think the important thing to do is that the facts come out".
For now, the president said the United States is waiting for the results of several investigations but will then make a "very strong statement". I've heard no tape.
Robert Mahoney, deputy executive director of the Committee to Protect Journalists, said: "U.N. involvement is the best guarantee against a Saudi whitewash or attempts by other governments to sweep the issue under the carpet to preserve lucrative business ties with Riyadh".
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