U.S.-based writer Jamal Khashoggi was strangled or suffocated as soon as he entered the Saudi Consulate in Istanbul and his body was subsequently dismembered and disposed of, Turkey's chief prosecutor said Wednesday.

After weeks of leaks, Irfan Fidan's comments mark the first detailed account by Turkish officials of what they believe happened to Khashoggi after he vanished on Oct. 2.

"In accordance with plans made in advance, the victim, Jamal Khashoggi, was strangled to death immediately after entering the Consulate General of Saudi Arabia," the prosecutor said in a statement.

"The victim's body was dismembered and destroyed following his death by suffocation — again, in line with the advance plans," the two-page statement read.

Fidan did not offer any evidence for his version of events.

The Turkish prosecutor also said that discussions with Saudi chief prosecutor Saud al-Mojeb yielded no "concrete results" despite Turkey's "well-intentioned efforts to reveal the truth."

Turkey is seeking the extradition of 18 suspects in the journalist's killing who were detained in Saudi Arabia. It is also pressing the kingdom for information on the location of Khashoggi's remains.

The death of Khashoggi — a Washington Post columnist and a critic of Saudi Arabia's de facto ruler, Crown Prince Mohammed bin Salman — sparked global outrage and left the kingdom facing a crisis.

Saudi Arabia has repeatedly shifted its account of what happened to Khashoggi after he entered its consulate almost a month ago.

President Donald Trump has called the effort to conceal Khashoggi's killing the "worst cover-up ever."

Secretary of State Mike Pompeo said Wednesday that Khashoggi's killing "violates the norms of international law" but re-emphasized the importance of what he described as a "long" and "strategic" U.S.-Saudi relationship.

"It's very important for us to keep that in mind as we continue to ensure the accountability of all those who were involved in committing this murder," he told Fox News Radio.

After vehement denials that Riyadh was involved in Khashoggi's disappearance, Saudi officials admitted Oct.19 that the dissident was killed inside the building.

But for days, they maintained that Khashoggi's death was a mistake when an attempt by rogue operatives to persuade him to return to Saudi Arabia escalated into a fatal fistfight.

Saudi Arabia's attorney general admitted Thursday that evidence shared by Turkish officials suggests that Khashoggi’s killing was "premeditated."

CLARIFICATION (Nov. 4, 2018, 11:05 a.m. ET): An earlier version of this article referred imprecisely to the news organization Pompeo spoke to. It was Fox News Radio, not Fox News.