"We have to get an outcome from this investigation as soon as possible".
Erdogan was informed of the conclusions Saturday, the Times reported, citing unnamed sources - and he has since dispatched officials to anonymously tell news outlets, including the Times.
Turkish security officials were working to identify the 15 individuals, English-language state broadcaster TRT World reported, adding that Turkish officials believe the Saudis may have taken the consulate's CCTV footage with them when they returned to Saudi Arabia.
Sen. Rand Paul, R-Ky., a longtime critic of the Saudi government, has said he'll try to force a vote in the Senate blocking US arms sales to Saudi Arabia. Sen. If he left [the consulate], you must prove this, you will prove this, even if it's with visuals. "The Saudi authorities have notified that they are open to cooperation in this regard and that the examination can be conducted in their consular buildings in Istanbul".
In response, U.S. Secretary of State Mike Pompeo urged the Saudi government to be "transparent" about the results of any investigation.
Government sources in Turkey said police believe the 59-year-old was killed inside the consulate, claims which Riyadh dismissed as "baseless". Turkey has said it will search the consulate for signs of what happened to Khashoggi, but has not said when it will do so.
"The information on the USA appointment of an investigator is not true", sources who asked not to be named due to restrictions on speaking to the media, told Anadolu Agency.
The newspaper said "a person close to the investigation" had shared the image with them.
Who is Jamal Khashoggi?
Meanwhile, the BBC published off-air audio from an interview Mr Khashoggi gave in London, three days before he disappeared.
"We demand from the worldwide community to pressure Saudi Arabia and Mohammed bin Salman to tell us exactly what happened".
Mr Khashoggi had gone to the consulate to collect divorce papers relating to his previous marriage, leaving his fiancee with his Saudi phone on the street outside.
In this February 1, 2015, file photo, Saudi journalist Jamal Khashoggi speaks during a press conference in Manama, Bahrain.
Khashoggi entered the consulate last Tuesday and has not been heard of or seen since, according to his fiancée and friends. Per the Times' source, the team's plan was "quick and complex", and the Saudi dissenter was dismembered "with a bone saw they brought for the objective".
"People who have long thought of themselves as Saudi's friends are saying this is a very, very serious matter", Jeremy Hunt said. "I do not like it", Trump told reporters at the White House.