A pro-government Turkish newspaper on Thursday pointed a finger at a Saudi security official close to Crown Prince Mohammed bin Salman over the disappearance of journalist Jamal Khashoggi, as Riyadh's ally Washington kept up its cautious stance.

More than two weeks since Khashoggi disappeared after stepping inside the Saudi consulate in Istanbul, neither Turkey nor the United States have publicly confirmed he is dead or said that Riyadh is to blame.

But with a steady stream of sometimes macabre claims leaked to the Turkish press, Riyadh is under increasing pressure to explain what happened to Khashoggi, a former regime insider who became critical of Prince Mohammed.

Turkish police overnight undertook a nine-hour search of the residence of the Saudi consul to Istanbul -- who abruptly left the country on Tuesday -- and also searched the consulate for the second time.

The controversy threatens to rip apart Prince Mohammed's attempt to portray himself as a modernising Arab ruler, with his planned investment conference in Riyadh next week hit by a litany of big name cancellations.

'Execution team head'

Turkish press reports -- which commentators suspect are based on deliberate government leaks -- have suggested that Khashoggi was killed by a 15-person "assassination team" who flew in on two chartered planes and then interrogated, tortured and killed him.

The pro-government Sabah newspaper on Thursday said Saudi security official Maher Abdulaziz Mutreb was the leader of the alleged team. He has been previously photographed close to the crown prince.

"Here is the head of the execution team," said Sabah's headline, and the paper then detailed Mutreb's movements on the day Khashoggi went missing.

Giving precise times based on CCTV footage, the newspaper reported that Mutreb went into the consulate more than three hours before Khashoggi entered the building.

In a series of CCTV images, Mutreb was then seen outside the consul's residence, then later at his hotel near the Saudi mission with a "large suitcase", and finally at the airport in the early evening.

Mutreb was then seen outside the consul's residence in another CCTV image, then later at his hotel near the Saudi mission with a "large suitcase" and finally at the airport in the early evening.

The pro-government Yeni Safak newspaper on Wednesday claimed it had heard audio tapes in which Khashoggi's alleged killers tortured him by cutting his fingers off before his decapitation.

But such details have yet to be aired publicly by the Turkish leadership under President Recep Tayyip Erdogan.

"Turkey is managing the process very carefully, successfully," Justice Minister Abdulhamit Gul said, without giving further details on the inquiry.

Riyadh has strongly denied involvement in Khashoggi's disappearance.

'US asked for tapes'

After US Secretary of State Mike Pompeo visited both Riyadh and Ankara, President Donald Trump Wednesday defended his cautious stance over Khashoggi, who was living in self-imposed exile in the US.

"I'm not giving cover (to Saudi Arabia) at all," he has insisted, vowing that the truth would come out within days.

He indicated that the US administration had not heard the tapes referred to by Yeni Safak and added he wanted Turkey share the evidence.

He said the United States had "asked for it (the tapes), if it exists. I am not sure yet that it exists, probably does, possibly does".

In the searches at the Saudi consul's residence, Turkish investigators were seen by AFP reporters paying particular attention to the garage and later left carrying evidence in bags and boxes.

Abdulkadir Selvi, a pro-government columnist in the Hurriyet newspaper, said Turkish investigators found that an "expert team" tried to remove evidence from the consulate.

Selvi said that despite the attempt, investigators were able obtain some evidence and added it would be correct to describe Khashoggi's disappearance as an "assassination".

'Iron Curtain'

The Washington Post Wednesday published what it said appeared to be Khashoggi's final column for the US newspaper, where he wrote of the importance of a free media in the Arab world.

"The Arab world is facing its own version of an Iron Curtain, imposed not by external actors but through domestic forces vying for power," he wrote.

"The Arab world needs a modern version of the old transnational media so citizens can be informed about global events. More important, we need to provide a platform for Arab voices."

The US newspaper said it had held off publishing the column in the hopes that he would return, but Global Opinions editor Karen Attiah accepted this was no longer possible.

The furore has also blown a huge hole in next week's Future Investment Initiative conference in Riyadh, which was meant to showcase Prince Mohammed's plans for reform.

French Economy Minister Bruno Le Maire on Thursday became the latest in an array of policy-makers and corporate chiefs to pull out. US Treasury Secretary Steven Mnuchin said he will decide later on Thursday whether to attend.