Mohammed bin Salman, the kingdom's de facto ruler, has not spoken publicly about the killing inside the Saudi consulate in Istanbul.

The CIA and some Western governments have said he ordered it, but Saudi officials say he had no role.

The death sparked a global uproar, tarnishing the Crown Prince's image and imperilling ambitious plans to diversify the economy of the world's top oil exporter and open up cloistered Saudi society. He has not since visited the United States or Europe.

"It happened under my watch. I get all the responsibility because it happened under my watch," he said.

Prince Mohammed made the comments to PBS' Martin Smith, according to a preview of a documentary, The Crown Prince of Saudi Arabia, which is set to air on October 1, ahead of the first anniversary of Khashoggi's death.

After initial denials, the official Saudi narrative blamed the murder on rogue operatives.

The public prosecutor said the then-deputy intelligence chief ordered the repatriation of Khashoggi, a royal insider who became an outspoken critic, but the lead negotiator ordered him killed after discussions for his return failed.

Saud al-Qahtani, a former top royal adviser whom Reuters reported gave orders over Skype to the killers, briefed the hit team on Khashoggi's activities before the operation, the prosecutor said.

Asked how the killing could happen without him knowing about it, Smith quotes Prince Mohammed as saying: "We have 20 million people. We have 3 million government employees."

Smith asked whether the killers could have taken private government jets, to which the Crown Prince responded: "I have officials, ministers to follow things, and they're responsible. They have the authority to do that."

A senior US administration official said in June the Trump administration was pressing Riyadh for "tangible progress" toward holding to account those behind the killing.

Eleven Saudi suspects have been put on trial in secretive proceedings but only a few hearings have been held.

A UN report has called for Prince Mohammed and other senior Saudi officials to be investigated.

Khashoggi, a Washington Post columnist, was last seen at the Saudi consulate in Istanbul on October 2, where he was to receive papers ahead of his wedding.

His body was reportedly dismembered and removed from the building, and his remains have not been found.

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