Saudi Arabia initially denied he was killed but last week acknowledged his death and put the blame on officials in the Saudi intelligence service.
The fallout has damaged Saudi Arabia, badly tarnished Crown Prince Mohammed bin Salman and raised questions about United States foreign policy priorities that hinge on the kingdom's financing or cooperation. Trump also said however the crown prince "strongly said that he had nothing to do with this, this was at a lower level".
The EU expects a "full, transparent investigation" of the killing of a Saudi journalist, said the bloc's foreign policy chief on Wednesday.
President Donald Trump had enthusiastically endorsed Crown Prince Mohammed bin Salman's consolidation of power, with the 33-year-old forging a close, chatty relationship with Trump's son-in-law and adviser Jared Kushner.
Trump has reiterated that he views Saudi Arabia as a great ally and an important purchaser of USA tanks, bombs and planes.
A Turkish senior official said, "How should a real investigation in Saudi Arabia work when one of the main suspects is the crown prince MBS?" referring to the crown prince by his initials.
After the journalist disappeared, Saudi Arabia initially insisted Khashoggi had walked out of the consulate after visiting the building on October 2.
Saudi Arabia has detained 18 people. "The incident is not justifiable", the crown prince said on a discussion panel at the conference.
"There are now those who are trying to take advantage of this painful situation to create a rift between the Kingdom and Turkey", he said.
"We're making very clear that the United States does not tolerate this kind of ruthless action to silence Mr Khashoggi, a journalist, through violence".
Instead, the two officials said, the operation with Khashoggi turned violent.
Mike Pence, the USA vice president, said the killing "will not go without an American response". When that failed, the writer, by their account, asked if he was going to be kidnapped. "You admit they did it, but why are they not saying (where)?" Turkish reports said a member of his entourage was involved in the crime.
His body was then rolled in a rug and given to a local "co-operator" to dispose of, the official said.
"Jamal Khashoggi's body still hasn't been found".
The leaks have also featured surveillance pictures of a Saudi agent wearing Khashoggi's clothes and a fake beard and leaving the consulate in an orchestrated bid to fool investigators into thinking the journalist had safely left the diplomatic mission. His fiancee, who was waiting outside the building for him, alerted authorities when he failed to come out.
"We call on the Sri Lankan government to condemn Khashoggi's killing and repression of Saudi journalists and dissidents, and raise these issues with the Saudi government", the FMM said.
The king assured Russian President Vladimir Putin in a phone call on Thursday that the Saudi government was determined to hold the guilty parties accountable and make sure "they receive their punishment", according to the official Saudi press agency.
In a speech timed to coincide with the start of a three-day worldwide business conference in Riyadh on Tuesday, Turkish President Recep Tayyip Erdogan rejected the Saudi narrative and said that Khashoggi's murder was planned in Riyadh.