ISIS has claimed responsibility for the recent attack in Germany, in which an Afghan asylum-seeker attacked train passengers with an ax and knife, injuring at least five people.
On Tuesday, a hand-painted ISIS flag was found in the terrorist's room.
The terrorist allegedly came to Germany two years ago as an unaccompanied minor and applied for asylum in March, according to The Guardian.
He had been living in a home for teenage refugees until two weeks ago, when he had been put in the care of a foster family.