A protester holds a sign saying "We will not leave without Jamal Khashoggi" outside the Saudi embassy in Istanbul on October 5, 2018.
Sources have told MEE that Khashoggi was tortured, murdered and dismembered by a hit squad of 15 Saudis sent to Istanbul to kill him. Mr Erdogan said in a speech to members of his AK Party in Ankara.
Khashoggi's killing has tainted the image of Crown Prince Mohammed bin Salman, who has positioned himself as a Saudi reformer, and tested ties between Washington and Riyadh as Western powers demand answers over his death.
Asked on the issue of extraditing the Saudi nationals now detained pending the investigation to Turkey, Al Jubeir stressed that "the individuals are of Saudi nationals, they are detained in Saudi Arabia, the investigation is in Saudi Arabia and they will be prosecuted in Saudi Arabia".
Central Intelligence Agency director Gina Haspel, who was in Turkey earlier this week to review evidence, briefed Trump in Washington on Thursday.
"There has been a declaration that he has been killed, but where is the body?"
"His local network in Turkey was very good, as you know, his political network as well", Cengiz told Haberturk.
Al-Jubeir addressed the Khashoggi case in a question-and-answer session, in which several reporters asked different questions about Saudi Arabia's handling of the case.More news: The Shale Boom Calmed Oil Markets, but for How Much Longer?
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Salah bin Jamal Khashoggi, the son of murdered dissident Saudi journalist Jamal Khashoggi has left Saudi Arabia.
Cengiz added that she wasn't sure how the Trump administration's conscience was affected by what happened.
Trump also said Riyad had staged the "worst cover-up ever" over the killing.
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 Khashoggi by mistake in a brawl. The Saudi news release, attributed to its public prosecutor, was significant because it relayed Turkey's conclusion, but it did not make clear whether Saudi investigators had reached that same conclusion on their own.
In his prepared remarks which he will give at the annual Manama Dialogue security conference in Bahrain, the U.S. official expressed that incidents like the killing of a Saudi journalist undermined Middle Eastern stability.
"You see, an important Saudi official uses an expression ... and we say it's now evident that he is killed, but where is it (the body)?"
Khashoggi and Cengiz had recently furnished an apartment for themselves in Istanbul.
"He thought Turkey is a safe country and if he would be held or interrogated, this issue would be swiftly solved".
Saudi Arabia is the lynchpin of a US-backed regional bloc against the growing Iranian influence in the Middle East but Khashoggi crisis has strained Riyadh's relations with the West.