ISTANBUL • Turkey has concluded that Jamal Khashoggi, a prominent journalist from Saudi Arabia, was killed in the Saudi Consulate in Istanbul last week by a Saudi team sent “specifically for the murder,” two people with knowledge of the probe said Saturday.

Turkish investigators believe a 15-member team “came from Saudi Arabia. It was a pre-planned murder,” said one of the people. Both spoke on condition of anonymity to discuss the ongoing investigation.

They offered no specific evidence to back up the account. Earlier Saturday, however, Turkey’s Anadolu news agency said the Istanbul public prosecutor’s office had opened a probe into Khashoggi’s disappearance. Turkish authorities have said Khashoggi never left the consulate.

Saudi Arabia had denied that Khashoggi, who contributed to The Washington Post’s Global Opinions section, was detained after he entered the mission.

In an interview with Bloomberg last week, Crown Prince Mohammed bin Salman said Khashoggi had left the consulate shortly after he arrived Tuesday. Saudi officials have yet to provide any evidence for that assertion.

The Saudi consul-general in Istanbul let Reuters news agency reporters tour the consulate Saturday, to show Khashoggi was not inside.

“… Jamal is not at the consulate nor in the Kingdom of Saudi Arabia, and the consulate and the embassy are working to search for him,” the consul-general, Mohammed al-Otaibi, was quoted as saying.

The U.S. is aware of The Post report but cannot confirm it, and does not know where Khashoggi is, a senior U.S. official said Saturday. The official spoke on condition of anonymity.

U.S. officials did not immediately comment on the Turkish conclusions.

The conflicting accounts appeared certain to deepen a rift between Saudi Arabia and Turkey, competing powers in the region.

The killing, if confirmed, would mark a startling escalation of Saudi Arabia’s effort to silence dissent. Under direction from the crown prince, Saudi authorities have carried out hundreds of arrests under the banner of national security, rounding up clerics, business executives and even women’s rights advocates.

“If the reports of Jamal’s murder are true, it is a monstrous and unfathomable act,” Fred Hiatt, the director of The Post’s editorial page, said in a statement. “Jamal was — or, as we hope, is — a committed, courageous journalist. He writes out of a sense of love for his country and deep faith in human dignity and freedom. He is respected in his country, in the Middle East and throughout the world. We have been enormously proud to publish his writings.”

Khashoggi may have been considered especially dangerous by the Saudi leadership, analysts said. His criticisms of the royal family and its power were delivered from his self-imposed exile in the U.S. and could not be dismissed as the complaints of a longtime dissident. Rather, he has long been a pillar of the Saudi establishment who was close to its ruling circles for decades and had been adviser to a former Saudi intelligence chief.

Khashoggi first visited the consulate Sept. 28 to obtain a document related to his upcoming wedding. He returned to the consulate Tuesday, concerned he might not be allowed to leave, according to his fiancee, Hatice Cengiz.

Khashoggi left his phone with her, along with instructions that she should call a member of Turkey’s governing party if he did not emerge. After waiting more than four hours, Cengiz called the police, she said.

Within a day, Turkish officials were saying they had no evidence Khashoggi had ever left the consulate while Saudis were insisting the journalist had left fairly quickly.

The episode was made more confounding by the thicket of security cameras around the consulate, monitoring its entrances. But neither government has released any video.

Tawakkol Karman of Yemen, the Nobel Peace Prize laureate for 2011, holds a picture of missing Saudi writer Jamal Khashoggi as she talks near the Saudi Arabia consulate in Istanbul on Friday.

thE associated press