One of the suspected killers of Saudi journalist Jamal Khashoggi was arrested at Roissy airport near Paris as he was about to board a flight to Riyadh, a police source and a judicial source said.
The police source named the detainee as Khaled Aedh Al-Otaibi, a former Royal Guard of Saudi Arabia.
The arrest came just days after French President Emmanuel Macron held face-to-face talks in Saudi Arabia with de facto ruler Crown Prince Mohammed bin Salman.
Mr Macron became the first major Western leader to visit the kingdom since Mr Khashoggi's murder.
Mr Khashoggi, a critic of Prince Mohammed, was last seen entering the Saudi consulate in Istanbul on 2 October 2018.
Turkish officials believe his body was dismembered and removed. His remains have not been found.
Al-Otaibi, who is mentioned on a British UK sanction list as being involved in Mr Khashoggi's murder, was also on a French wanted list.
He was arrested on the basis of a warrant issued by Turkey in 2019, the police source told Reuters.
French prosecutors will now begin proceedings for a potential extradition there.
"He was involved in the unlawful killing of Jamal Khashoggi in Istanbul on 2 October 2018, as part of the 15 man team sent to Turkey by Saudi authorities," the report by Britain's Office of Financial Sanctions Implementation said.
Mr Al-Otaibi, born in 1988, "was involved in the concealment of evidence at the Saudi General Consul's residence following the killing", that report said.
A US intelligence report released in March said Prince Mohammed had approved the operation to kill or capture Khashoggi.
The Saudi government has denied any involvement by the crown prince and rejected the report's findings.
Mr Khashoggi's fiancée Hatice Cengiz has welcomed the arrest.
"France should try him for his crime, or extradite him to a country able and willing to genuinely investigate and prosecute him as well as the person who gave the order to murder Jamal", she said in a tweet.