Istanbul, Turkey (CNN) Turkish officials suspected within hours of Saudi journalist Jamal Khashoggi's disappearance that he had likely been killed and raced to Istanbul airport to intercept a private Saudi plane that was waiting to take off, CNN has learned.

After discovering that Khashoggi had vanished, intelligence officers scrambled to try and find out whether he had been abducted or whether his body was being taken out of the country.

Disguised as airport staff, officers searched the plane while a group of Saudis waited in the airport. But they found nothing suspicious, and the flight in question was allowed to leave at about 11 p.m. local time.

In the two weeks since, authorities have been trying to piece together what happened on that fateful afternoon, when the Washington Post columnist walked into the Saudi consulate to obtain paperwork to marry his Turkish fiancée -- and was never seen again.

Turkish officials now say they believe that 15 Saudi men who arrived in Istanbul on October 2 were connected to Khashoggi's death. At least some of them appear to have high-level connections in the Saudi government.

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