(CNN) In an op-ed published Friday in The Washington Post, Turkish President Recep Tayyip Erdogan wrote about the questions surrounding Jamal Khashoggi's death and says the order to kill him came "from the highest levels of the Saudi government."

The piece, posted by the US newspaper that Khashoggi worked for, is the most direct accusation made by Erdogan to date against the Saudis.

Khashoggi, 59, was last seen alive around lunchtime on October 2 entering Saudi Arabia's Istanbul consulate, where he hoped to obtain paperwork that would have allowed him to marry Hatice Cengiz, a Turkish national. When he failed to re-emerge, his fiancée -- who was waiting outside -- alerted Turkish authorities that something was wrong.

Erdogan explained in the op-ed that a month after the Khashoggi's death, Ankara still does not know where Khashoggi's remains are. He called Khashoggi's killing "inexplicable."

Recep Tayyip Erdogan

Erdogan added that he does not believe Saudi Arabia's monarch had Khashoggi, a Saudi journalist who was critical of the government, killed.

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