Saudi Arabia acknowledged on Thursday that the murder of journalist Jamal Khashoggi appeared to have been premeditated, based on information from Turkey, as it sought to draw a line under the crisis.

It was the latest twist in the shifting official narrative of the October 2 killing which US President Donald Trump has derided as “one of the worst cover-ups” in history.

The Saudi public prosecutor said he was making the latest assessment on the basis of evidence supplied by Turkey which has been the source of the spate of grisly revelations about the government critic's death that triggered an international outcry.

After first insisting Khashoggi left the consulate unharmed, Saudi authorities said he was killed in an argument that degenerated into a brawl, then admitted he was murdered before finally accepting what Turkey had said virtually from the start — that he was killed in a premeditated hit.

As the Saudi public prosecutor made the new admission on Thursday, Turkish Foreign Minister Mevlut Cavusoglu said Riyadh still needed to provide answers to remaining questions, such as who ordered the hit and what happened to Khashoggi's body.

“Information from the Turkish authorities indicates that the act of the suspects in the Khashoggi case was premeditated,” the office of public prosecutor Sheikh Saud al-Mojeb said in a statement carried by the state-run Saudi Press Agency.

“The public prosecution continues its investigation with suspects... to complete the course of justice.”

The slow drip of admissions cast a pall over a showcase three-day investment forum that was closing on Thursday with organisers putting a brave face on the array of no-shows among big-name guests.

The Saudi energy minister said foreign companies which boycotted the Future Investment Forum (FII) had “apologised” and vowed a return to normal ties.

“Some companies abstained from the conference due to political pressure as a result of an odious campaign directed from outside the kingdom which has failed,” Khalid al-Falih told state-run Al-Ekhbariya news channel.

“All the companies that abstained have been calling us during the past 48 hours to apologise and express regret,” and vowed to open offices and restore normal relations, Falih said.

Turkey says questions remain

Economy and Planning Minister Mohammed al-Tuwaijri told the conference that Saudi oil giant Aramco was “absolutely ready” for its long-awaited massive IPO although several regulatory procedures remained.

The investment conference, dubbed “Davos in the desert”, aimed at drawing foreign investors to help Riyadh diversify its oil-reliant economy.

A long list of investors and international policymakers declined to show up in Riyadh over the Khashoggi murder.

Siemens chief executive Joe Kaeser, corporate chiefs from JP Morgan, Ford and Uber, and media powerhouses like CNN and the Financial Times all scrapped plans to attend.

Ministers from Britain and France and the United States also stayed away.

On Saturday, more than two weeks after Khashoggi's disappearance, Riyadh said the Saudi journalist was murdered during “a brawl” inside the kingdom's Istanbul consulate.

Saudi Arabia's powerful Crown Prince Mohammed bin Salman denounced the “repulsive” murder and vowed justice will prevail, in his first public comments on the case at the investment forum on Wednesday.

Saudi authorities have also announced the arrest of 18 Saudis in connection with his death.

But “there are still questions that need answers” over the murder, the Turkish foreign minister said Thursday, demanding that Riyadh explain why the 18 were arrested.

“Who gave them the orders?” Cavusoglu asked, pointing out that Khashoggi's body had still not been found.

“Where is (the body)? You admit they did it, but why are they not saying (where)?” he told a press conference in Ankara.