During the searches of al-Bakr's friend's flat, the police found "highly-volatile explosives", which were said to be more dangerous than TNT [REF].
According to terror expert Elmar Theveßen of German public ZDF broadcaster, the found explosive was TATP, which were also used in the November 2015 Paris attacks and the 2016 Brussels bombings and which is difficult to fabricate [REF].