Turkey vowed on Saturday to uncover the truth behind Saudi journalist Jamal Khashoggi's killing, as international outrage over Riyadh's most recent explanation grows.

Sources close to President Recep Tayyip Erdogan have told Middle East Eye the Turkish leader is determined to see all the details behind the apparent murder publicly revealed, a sentiment repeated on Saturday by the spokesman of his ruling Justice and Development Party.

"Turkey will reveal whatever had happened. Nobody should ever doubt about it," Omer Celik said, according to the official Anadolu news agency.

In a stunning about-face, on Friday night Saudi Arabia admitted that Khashoggi was killed on 2 October in its consulate in Istanbul, claiming the journalist died in a fist-fight that broke out unintentionally.

Turkey will reveal whatever had happened. Nobody should ever doubt about it - Omer Celik, AKP spokesman

But Turkish authorities are not satisfied with the Saudi explanation, a high-level source told MEE, and are collecting strong, mounting evidence that Khashoggi was the victim of a premeditated murder.

Turkish sources previously told MEE that they have evidence that Khashoggi was tortured, murdered and dismembered by a 15-man strong hit squad. It took Khashoggi seven minutes to die, the sources said.

Turkish sources have now told MEE that they are seeking the extradition of the 15 Saudis.

However, the sources said Ankara is extremely concerned that the suspects will be arrested and executed by Saudi authorities before Turkish investigators can have the opportunity to question them.

The Saudi attorney-general has said that 18 suspects have been taken into custody so far.

Unexplained by the Saudi statements on Friday was the presence of forensic pathologist Salah Muhammad al-Tubaigy in the party sent to meet Khashoggi in the consulate.

Tubaigy is an expert at speedy autopsies, MEE has learned.

Similarly unexplained is the bone-saw that was widely reported to have been brought to Istanbul from Riyadh by the Saudi team and used on Khashoggi.

Missing body

From the outset, Riyadh claimed Khashoggi, a leading critic of the Saudi government, left the consulate soon after arriving.

Two days after Khashoggi's disappearance, Saudi Crown Prince Mohammed bin Salman told Bloomberg News that the journalist had left the consulate.

"Yes, he's not inside," the heir to the Saudi throne said. "My understanding is he entered and he got out after a few minutes or one hour."

However, a drip feed of details from a Turkish investigation appears to have forced Riyadh into admitting that Khashoggi did, in fact, die in the Saudi consulate.

Over the past week, investigators have been searching for the body of Khashoggi, which sources told MEE was begun to be dismembered before the journalist had died.

The Turkish prosecutor-general is writing up a report on Khashoggi's killing, but will not publish it until a body is found, MEE understands. The prosecutor-general has waited three days as investigators have scoured the consulate, the consul-general's home and woodland on Istanbul's outskirts.

Saudi Arabia acknowledged on Friday that there had been attempts to cover up the killing, but it has not released any information publicly on what happened to Khashoggi's body.

Jamal Khashoggi: The Saudi insider who spoke up for free speech Read More »

In a statement published by the state Saudi Press Agency, an unidentified Saudi official said: "The preliminary investigations conducted by the Public Prosecution showed that the suspect[s] had travelled to Istanbul to meet with the citizen Jamal Khashoggi as there were indications of the possibility of his returning back to the country."

It added that discussions with Khashoggi in the consulate "did not go as required and developed in a negative way, leading to a fight" that in turn led to the journalist's death "and to their attempt to conceal and cover what happened".

However, sources have told MEE that Khashoggi was killed by an injection of drugs, likely morphine, after being tortured.

Were his remains to be found, traces of the drug may be found, asking new questions of Saudi Arabia's fist-fight narrative.

Rights group Amnesty International called on Saudi Arabia to release the body.

"We call on the Saudi Arabian authorities to immediately produce Jamal Khashoggi's body so an autopsy can be performed by independent forensic experts in accordance with international standards," Amnesty's Samah Hadid said in a statement.

The last known image of Khashoggi walking into the consulate. (Handout)

Erdogan and Saudi King Salman spoke by phone on Friday night, agreeing to continue cooperation and exchanging details on the case, the Turkish presidency said in a statement.

A Turkish official told the Reuters news agency that investigators were obtaining samples of Khashoggi's DNA from within Turkey and did not require them from Saudi Arabia.

Aides implicated

The two most prominent Saudis to be implicated by the Saudi investigation into Khashoggi's death are deputy intelligence chief General Ahmed al-Assiri and the crown prince's top aide, Saoud al-Qahtani, both of whom have been sacked.

Their departures appear to be an attempt to absolve Mohammed bin Salman, commonly known as MBS, of blame.

In the wake of their departure, MBS has been charged by his father with reforming the intelligence services.

Do you think I make decisions without guidance? I am an employee and a faithful executor of the orders of my lord the king and my lord the faithful crown prince - Saoud al-Qahtani, MBS aide

However, Qahtani himself has previously admitted he acts only according to the wishes of the crown prince.

"Do you think I make decisions without guidance? I am an employee and a faithful executor of the orders of my lord the king and my lord the faithful crown prince," he tweeted last year.

Shortly before his death, Khashoggi told MEE that Qahtani personally informed him in 2017 that he was banned from writing or tweeting, following remarks the veteran journalist made about his country's relationship with US President Donald Trump.

Khashoggi said Qahtani also led efforts to convince him to return to Saudi Arabia after fleeing the country, the journalist told MEE.

Khashoggi was made to understand that Qahtani was acting on MBS's orders, he said.

Last week, MEE revealed that seven of the 15-strong hit squad were members of the crown prince's bodyguard.

International outcry

Trump, who has cultivated close ties with King Salman and MBS, has expressed confidence in the Saudi story, on Friday calling it credible and adding it was "a good first step".

Asked on Saturday during a trip to Nevada if he was satisfied that Saudi officials had been fired over Khashoggi's death, Trump said: "No, I am not satisfied until we find the answer. But it was a big first step, it was a good first step. But I want to get to the answer."

Yet Trump also warned against halting a massive arms deal with Riyadh, saying it would hurt American jobs, despite the international furore over Khashoggi's death.

Still, his stance seems to pull up short of the prevailing view within the US intelligence services, who believe MBS to be culpable for Khashoggi's death, according to the New York Times.

Activists dressed as US President Donald Trump and Saudi Crown Prince Mohammad bin Salman participate in a demonstration calling for sanctions against Saudi Arabia and against the disappearance of Saudi journalist Jamal Khashoggi. (Reuters) Many leaders, both in Washington and elsewhere, have expressed extreme scepticism regarding the Saudi explanation.

"To say that I am skeptical of the new Saudi narrative about Mr Khashoggi is an understatement," said senior Republican Senator Lindsey Graham, who earlier called for Saudi Arabia to be sanctioned.

"First we were told Mr Khashoggi supposedly left the consulate and there was blanket denial of any Saudi involvement. Now, a fight breaks out and he's killed in the consulate, all without knowledge of Crown Prince," he tweeted.

First we were told Mr. Khashoggi supposedly left the consulate and there was blanket denial of any Saudi involvement. Now, a fight breaks out and he’s killed in the consulate, all without knowledge of Crown Prince. — Lindsey Graham (@LindseyGrahamSC) October 19, 2018

Similarly, Democratic representative Adam Schiff tweeted: "The claim that Khashoggi was killed while brawling with 15 men dispatched from Saudi Arabia is not at all credible. If he was fighting with those sent to capture or kill him, it was for his life."

The EU's top diplomat, Federica Mogherini, called for a thorough investigation into the "deeply troubling" death of Khashoggi and full accountability for those responsible.

The EU statement echoed earlier condemnations from member countries France and Germany.

German Chancellor Angela Merkel cast doubt on the Saudi version of Khashoggi's death, saying that the "horrific" events "haven't been cleared up and of course we demand that they be cleared up".

French Foreign Minister Jean-Yves Le Drian demanded an "exhaustive and diligent investigation".

The United Kingdom, whose trade minister pulled out of a major investment conference in Riyadh next week as the scandal escalated, said it was considering its "next steps".

"As the foreign secretary has said, this was a terrible act and those responsible must be held to account," it said in a statement.

Meanwhile, United Nations Secretary-General Antonio Guterres said he was "deeply troubled" by the confirmation of Khashoggi's killing, his spokesman said.

The head of the UN "stresses the need for a prompt, thorough and transparent investigation into the circumstances of Mr Khashoggi's death and full accountability for those responsible," according to his spokesman.

On Saturday, the Washington Post’s publisher and CEO, Fred Ryan, for whom Khashoggi wrote columns, said in a statement: “The Government of Saudi Arabia has shamefully and repeatedly offered one lie after another in the nearly three weeks since Jamal Khashoggi disappeared in their Istanbul consulate. Offering no proof, and contrary to all available evidence, they now expect the world to believe that Jamal died in a fight following a discussion. This is not an explanation; it is a coverup. President Trump, Congress and leaders of the civilized world should demand to see verifiable evidence. The Saudis cannot be allowed to fabricate a face-saving solution to an atrocity that appears to have been directed by the highest levels of their government.”

In contrast, Saudi Arabia's Arab allies have lept to its defence.

Egypt called King Salman's actions "brave" and "decisive," adding that they show the Saudi leader's "respect for law".

The United Arab Emirates commended King Salman's actions, and Bahrain said "Saudi Arabia will remain a state of justice, values and principles".