Mohammed Emwazi - the Islamic State militant known as Jihadi John - "knew he would die" and was always wary of a potential drone strike, a journalist who met the British terrorist said.
US military officials believe Emwazi, who was responsible for the deaths of several Western hostages, was killed in a targeted drone attack in Syria.
Jürgen Todenhöfer, a German journalist who was allowed unprecedented access to IS in Syria and Iraq, said Emwazi was always "opening the window of his car to look if a drone was over us".
"He knew people were trying to kill him," Mr Todenhöfer said.
The journalist said Emwazi was "very cautious" and was always wearing a scarf over his face.
Todenhöfer recalled an incident where the militant got "extremely angry" when he saw his uncovered face.
Todenhöfer described Emwazi as a "horrible killer" who was "frightening" and "always thought it necessary to threaten people".
"He was never laughing, making a joke or saying something nice - he was always very rude," he said.