The State Criminal Police Office (LKA) in the German state of North Rhine-Westphalia (NRW) apparently shared intelligence (indicating that Amri was plotting a terrorist attack in Germany) with the local federal interior ministry office in Dusseldorf in March 2016 – over half a year before the December attack.

In a confidential letter, seen by Bild am Sonntag, police stated that "according to the data available so far, the forecast can be made that Amri poses a terrorist threat in the form of a (suicide) attack," citing as evidence some messages the future attacker sent in a chat on February 2, which was monitored by law enforcement.

In a string of cryptic messages, Amri allegedly wrote he was going to marry "a sister" in Germany. As his conversation partner appeared to be unaware of what that meant, Amri clarified his intentions, using the word "Dougma."