Turkish authorities foiled a "major" attack in Istanbul on the same day as terrorist attacks in Paris.
Police on November 13 detained five people in Istanbul, including a suspected associate of the notorious Islamic State (IS) group militant known as "Jihadi John" who the United States believes was killed in a recent drone strike in Syria.
Aine Lesley Davis, a British citizen who guarded foreign prisoners in Syria, was among the IS suspects detained in an operation in Istanbul.
Davis and the other four militants had crossed into Turkey from Syria at an unspecified date.
Turkish authorities are investigating if the foiled plot had any links with the Paris attacks that killed 132 people.
"Jihadi John", whose real name is Mohammed Emwazi, is the masked figure who appeared in a series of graphic videos showing the beheading of Western hostages.