The Saudi officials who killed journalist Jamal Khashoggi in their Istanbul consulate must reveal the location of his body, Turkey's president said as he sharply criticised the kingdom's handling of the case.
Recep Tayyip Erdogan also said Saudi Arabia's chief prosecutor will arrive in Turkey on Sunday as part of the investigation and will meet Turkish counterparts.
Turkey's state-run news agency said Turkish prosecutors plan to seek the extradition of 18 suspects.
Anadolu Agency said the Istanbul chief prosecutor's office submitted its request to the justice ministry, and the foreign ministry will formally request the extraditions.
On Thursday, Saudi prosecutors said Khashoggi's killing was premeditated, citing Turkish evidence and changing the country's account again to try to ease international outrage over the murder of a prominent critic of crown prince Mohammed bin Salman.
Turkey has other "information and evidence" about the killing by Saudi officials after Khashoggi entered the consulate on 2 October, and it will eventually reveal that information, Mr Erdogan said.
"There is no point in being too hasty," he said in an indication that Turkey is prepared to maintain pressure on Saudi Arabia, even as the kingdom struggles for ways to end the crisis.
CIA director Gina Haspel was in Turkey earlier this week to review evidence, and she briefed Donald Trump in Washington on Thursday.
What the US president called "one of the worst cover-ups in the history of cover-ups" was revealed to the world by Turkish leaks of information, including references to purported audio recordings of the killing, and security camera footage of the Saudi officials involved as they moved around Istanbul.
Key mysteries remaining include whether the killing was carried out with the knowledge of the crown prince, who denies it, and the location of Khashoggi's body.
"It is clear that he has been killed but where is it? You have to show the body," Mr Erdogan said during an address to Turkey's ruling party leaders.
He criticised initial Saudi statements that claimed Khashoggi had left the consulate unharmed after going there for paperwork related to his planned marriage to a Turkish woman.
"He will leave the consulate and not take his fiancee with him? Such childish statements do not go hand in hand with statesmanship," said Mr Erdogan, again urging Saudi Arabia to turn over 18 suspects the kingdom said it had arrested and would punish for the crime.
"If you cannot get them to speak ... then hand them over to us and let us put them on trial," he added.
Mr Khashoggi's son Salah has left Saudi Arabia after the kingdom revoked a travel ban, allowing him to travel to the US.
Mr Khashoggi's fiancee said later that she has not received any condolence call from Saudi officials.
Hatice Cengiz, who is Turkish, also said in an interview on Turkish television channel HaberTurk: "I found myself in a darkness I cannot express."
She said she had asked US secretary of state Mike Pompeo, who called her about the case, whether he had any news that would make her happy.
"But he said he didn't," she added.
State department spokesperson Robert Palladino said Washington welcomed the decision to have Salah Khashoggi and his family leave Saudi Arabia. His US destination was not immediately known but his late father lived in the Washington area.
The statement from Saudi prosecutors that evidence showed Khashoggi's killing was premeditated contradicted an earlier Saudi assertion that rogue officials from the kingdom had killed him by mistake in a brawl.
That assertion, in turn, backtracked from an initial statement that Saudi authorities knew nothing about what happened to the columnist for the Washington Post.
The shifting explanations indicate Saudi Arabia is scrambling for a way out of the crisis that has enveloped the world's largest oil exporter and a major US ally in the Middle East.
But a solution seems a long way off, partly because of deepening scepticism in Turkey and elsewhere that the brazen crime could have been carried out without the involvement of Prince Mohammed, the kingdom's heir apparent.
If you want to read how the day's developments happened live, please see what was our live coverage below
Please allow a moment for the live blog to load
Good morning and welcome to the latest in the diplomatic fallout from the murder of Jamal Khashoggi.
Saudi Arabia initially denied involvement in the journalist's disappearance, but eventually attributed his death to a botched attempt to return him to the kingdom. However, Turkey has dismissed Saudi efforts to blame rogue operatives and urged it to search "top to bottom" for those responsible.
The director of the CIA, Gina Haspel, who departed for a trip to Turkey on Monday, has listened to an audio recording of Khashoggi's interrogation and killing, sources told The Washington Post.
It comes after Saudi Arabia's crown prince, Mohammed bin Salman, vowed that the killers would be brought to justice in his first public comments since the journalist's murder.
Here is everything we know so far about the killing of Khashoggi, from our Middle East correspondent, Richard Hall.
Everything we know about the death of Jamal KhashoggiThree weeks ago, the dissident journalist Jamal Khashoggi walked into the Saudi consulate in Istanbul to collect paperwork he needed to get married. He was never heard from again. What followed was a gruesome spectacle of leaks and lies in which Saudi Arabia denied any knowledge of Khashoggi’s whereabouts, while Turkish investigators drip-fed details of their investigation to the press.
On Wednesday, Turkish media published security camera images allegedly showing a vehicle belonging to the Saudi consulate "scouting" a forest on the outskirts of Istanbul before Khashoggi was murdered.
The image obtained by state television TRT and other media shows a black car with a diplomatic license plate at an entrance to Belgrade Forest.
On Tuesday, Turkey's president, Recep Tayyip Erdogan, said consulate officials had made "reconnaissance" trips to the forest as well as the city of Yalova a day before Khashoggi was killed.
Saudi Arabia, the world's top oil exporter, has come under increasing pressure over the death of Khashoggi, a columnist and one of the crown prince's most prominent critics.
The crisis has strained Riyadh's ties with the West and led dozens of politicians, top world bankers and company executives to boycott an investment conference that opened in Riyadh on Tuesday, dubbed "Davos in the Desert".
Saudi Arabia's crown prince, Mohammed bin Salman said on Wednesday that Khashoggi's killing was a “heinous crime that is painful to all Saudis” in his first public comments since the furore over the murder.
Saudi crown prince says Jamal Khashoggi's murder is a 'heinous crime that cannot be justified'In his first public comments since the killing, Mohammed bin Salman said: ‘All legal things [are being done] to finalise the investigation to co-operate with the Turkish government, to present the perpetrators to the court’
Saudi Arabia's crown prince, Mohammed bin Salman, said Saudi Arabia and Turkey would work together "to reach results" on a joint investigation and described cooperation between the two countries as "special", despite criticism from Ankara.
"The incident that happened is very painful, for all Saudis ... The incident is not justifiable," the crown prince said on a discussion panel at the conference in Riyadh.
Turkey's president, Recep Tayyip Erdogan, spoke to Prince Mohammed on Wednesday and the two discussed the steps needed to bring to light all aspects of Khashoggi's death, a presidential source told Reuters.
But in the bluntest sign yet of strained ties, one of Mr Erdogan's advisers wrote in a Turkish newspaper that Prince Mohammed had "blood on his hands".
Theresa May has said the UK will revoke the visas of those suspected of involvement in killing Khashoggi. She said Saudi Arabia's claim the journalist died in a fist fight "does not amount to a credible explanation".
Also on Wednesday, Saudi officials gave Turkish police permission to search a well at the Saudi consulate in Istanbul as part of their investigation into Khashoggi's disappearance.
Reuters has cited two sources saying the director of the CIA, Gina Haspel, heard an audio recording of the killing of Khashoggi during her visit to Turkey.
Turkish authorities have been focusing on a well in the garden of Saudi Arabia's consulate as part of its investigation into Khashoggi's death. His body is still missing.
Yeni Safak, a pro-government Turkish newspaper, said investigators emptied the well and were awaiting the results of an analysis of the water to determine whether body parts were dumped there.
But Sabah, another pro-government newspaper, said Saudi Arabia has yet to give Turkish authorities permission for a search.
Join our new commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies