A senior Turkish official told CNN that "it is clear that the judicial system in Turkey is better equipped to genuinely serve the cause of justice in this case," and that court proceedings in Turkey would be open to international observers.

After Saudi Arabia admitted that Khashoggi was killed October 2 in its Istanbul consulate, five high-ranking officials were dismissed, including Saudi Crown Prince Mohammed bin Salman's media chief and the deputy head of the Saudi intelligence service. Eighteen people were arrested.

Riyadh has maintained that neither bin Salman nor King Salman knew of the operation to target Khashoggi. US officials have said such a mission -- including 15 men sent from Riyadh -- could not have been carried out without the authorization of bin Salman, the country's de facto ruler.

Turkish officials played the purported audio of Khashoggi's killing to CIA Director Gina Haspel, according to two sources familiar with Haspel's meetings in Turkey this week.

Erdogan described some of the statements made by Saudi authorities as the Khashoggi case unfolded as "very funny" and said their strangeness had increased the Turkish authorities' responsibility to act.

"These juvenile statements do not match with the seriousness of government affairs," he said. "It is obvious that (Khashoggi) is killed. But where? Where is the body?"

He also suggested that the Turkish authorities had further significant information in their possession, saying: "It's not like we don't have other documents... Tomorrow is another day."

Fiancée: He did not want to go

Khashoggi's fiancée, Hatice Cengiz, told Turkish broadcaster Haberturk on Friday that the journalist had been concerned about going to the Saudi consulate in order to obtain paperwork allowing him to remarry, fearing tensions might arise.

"Of course, he did not want to go," she said.

Nonetheless, he did not fear arrest, Cengiz told Haberturk, according to the Reuters news agency. "His local network in Turkey was very good as you know, his political network as well," Cengiz said. "He thought Turkey is a safe country and if he would be held or interrogated, this issue would be swiftly solved."

Cengiz said her expectation now was the same as Erdogan's: for those responsible for Khashoggi's death to be tried.

Speaking about an invitation she received from US President Donald Trump to visit the White House, Cengiz said, "The statements Trump made in the first days around his invite and the statements he made afterward opposed each other. They were simply statements to gain public sympathy."

She added that US Secretary of State Mike Pompeo called her a couple of days later. "I think the call was about showing that they were serious after Trump's statements," she said.

Cengiz said nobody in Saudi Arabia had called her.

In his will, Khashoggi said he wanted to be buried in the Saudi city of Medina, she said, adding that she hoped that this would happen when his body is found. Asked if she would visit him there, her response was negative.