Politicians gathered at Berlin's Breitscheidplatz on Wednesday to lay wreaths in remembrance of the 12 people who lost their lives in the 2016 terror attack on the square's Christmas market.
While anniversary commemorations focused on the victims and their loved ones, German lawmakers are still trying to piece together the puzzle around the attacker Anis Amri.
German authorities knew about him long before he stole a semi truck, killed the driver and finally drove the vehicle into an unprotected Christmas market at Berlin's Breitscheidplatz.
More than 60 people were wounded, some of whom seriously, in the attack on December 19, 2016. Amri, a rejected asylum-seeker from Tunisia, was later shot to death by authorities in Italy while on the run.
Already in 2017, special investigator Bruno Jost, who was commissioned by the Berlin Senate to investigate the case, wondered why the previously convicted and rejected asylum-seeker was still at large, despite his status as a known drug dealer.
So far, no one has come up with a plausible answer — neither the state inquiries in Berlin and North Rhine-Westphalia nor the parliamentary inquiry set up by the Bundestag in March have found a reason.
Attacker's social media profiles left unmonitored
In mid-November, a witness from Germany's domestic intelligence agency (BfV) who was working on evaluating Islamist websites at the time of the attack was summoned to speak to the German parliamentary inquiry committee.
Although Amri was regularly a topic of conversation within the inter-agency terrorism defense unit (GTAZ), no one was apparently monitoring the social media activities of the future attacker.
Amri's Facebook profile was ignored as well as several relevant chat groups, inquiry committee member and Left party lawmaker Martina Renner told DW.
"What do they actually do?" she wondered, adding that it's possible that the BfV and other security agencies want to distract from their own mistakes and miscalculations.
For Renner, their reactions boil down to two possibilities: "Did they not do the right thing? Or are they not telling us the truth?"
Taking the German government to court
Renner's distrust of the authorities stems from the restrictive way the findings from ongoing court cases are being handled.
The Bundestag committee has not received any case files from the trial of Abu Walaa, who is the alleged leader of the militant "Islamic State" (IS) in Germany. It is almost certain that Amri knew him.
The committee is also blocked from having access to so-called "handlers" who give concrete orders to informants in Islamist circles.
For these reasons, the Left party teamed up with the Greens and the business-friendly Free Democrats (FDP) to file a complaint against the German government with the Constitutional Court.
Parallels to NSU terror case
For Renner, the government's attitude in the Amri case goes far beyond what she experienced with investigations into the far-right terror group, the "National Socialist Underground" (NSU).
The NSU case is also being investigated in several federal and state inquiries — but with one big difference: the courts made case documents available to the committees. Informant handlers were also able to be summoned for questioning by lawmakers.
Armin Schuster, who also heads the Bundestag inquiry into the Berlin terror attack, said that it was incorrect to compare the two cases.
He told DW that the informants and their handlers who were involved in the NSU case only testified after they were no longer active — something that is not possible with the informant handlers in the Amri case.
Reduced surveillance was a 'mistake'
Amri frequently stayed at the now-closed Fussilet mosque in Berlin, which was regarded as a hotspot for the radical Salafist scene. Authorities apparently failed, however, in placing informants directly with Amri.
Schuster told DW that security agencies made a "mistake" when they decided not to observe Amri as closely in the latter half of 2016 "because they were unsuccessful with all their attempts in the first half of the year."
After comparing surveillance data, authorities were able to determine that Amri was prepared to use violence. Despite this, he was able to carry out a truck attack unhindered.
For Schuster, one thing is clear — "I want someone in the terror defense center to take the lead in such a case."
In GTAZ, however, poses a challenge as there are several other agencies involved. What is apparently missing is a clear hierarchy and managerial authority.