It seems the Berlin Christmas market attack in December 2016 was preceded by bigger security problems than previously imagined.

On Thursday, Germany's federal parliament is beginning a fresh investigation into the case of Anis Amri, the Tunisian asylum seeker who drove a truck into a crowd in central Berlin a few days before Christmas, killing 12 people and injuring several dozen more. He had previously murdered the truck's Polish driver and was himself killed a few days later by Italian police while on the run.

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In the months that followed, it was revealed that Germany's state and federal security forces had made a series of mistakes. Intelligence agencies were criticized for failing to track Amri before the attack, even though he had been identified as a potential threat, and had indeed briefly been in custody for drug dealing.

Moreover, immigration offices around the country faced scrutiny because Amri had apparently been able to register as an asylum seeker under various aliases and nationalities.

The bigger picture

The state governments of Berlin and North Rhine-Westphalia launched their own investigations last year. The German capital commissioned semi-retired state prosecutor Bruno Jost as a special investigator, who presented a damning report in October 2017 that stated the authorities "did everything wrong you could possibly do wrong."

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But, as the report was limited to failures in one state alone, Berlin Interior Minister Andreas Geisel recommended that the Bundestag re-examine the issue.

And yet, the new investigation is not just there to fill in the gaps left by previous investigations. As the head of the Bundestag committee, Armin Schuster indicated earlier this week there remains a lingering sense that Germany owed more clarification to the victims and their families, many of whom were foreign nationals.

As the federal commissioner for the victims, Kurt Beck, and his Berlin counterpart, Roland Weber, found out in the aftermath of the attack, many families of the victims said they had been neglected by authorities. Information was slow to emerge, and Berlin Mayor Michael Müller was criticized was waiting two months to send out condolence letters.

What went wrong?

"The big questions, namely about what went wrong at higher levels, can only be answered in a limited way by state investigations," Weber told DW. "The victims still want a more thorough explanation of what went wrong."

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Weber has spent months in close contact with many of the victims' families, and said that many still had questions: Why did the authorities allow a clearly dangerous man out of their sight? Why was he able to go into the mosque where he apparently became radicalized? Why did they believe he could lead them to other men in the background, which he couldn't? Why did the Tunisian government wait so long to send evidence of who he was?

A lot is already known about Amri's whereabouts in the months before the Berlin attack. He entered Germany in July 2015, applying for asylum in the southern city of Freiburg, after having spent four years in a Sicilian jail for arson and physical assault. Over the next 15 months, he used at least 14 aliases to either apply for asylum or social benefits around Germany; most of the applications were rejected. At various times, he made contact with radical Islamist networks, dealt and consumed drugs, was under observation by domestic intelligence agencies, and even at one point told police informants about possible attacks — one of the many warning signs that was either not passed on or not acted upon.

The failure of communication between immigration offices and security offices at both the federal and state levels in Germany has been under particular scrutiny.

What is being done?

"But the families also want to know: What has Germany learned about how security forces will operate differently in future?" said Weber. "And when something does happen, they want to know how Germany will act differently in dealing with victims."

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In the meantime, the German government has done more to make amends with victims' families: Last December, Angela Merkel invited them to the Chancellery to discuss their concerns, and promised that Germany would change how it deals with such attacks going forward. The pledge to improve victims' protection was also included in the new government coalition contract between Merkel's Christian Democrats and the Social Democrats.

"I can't speak for all of the victims' families, but after those events, one of the victims told me that that had helped," said Weber. "Before he always had the feeling that politicians didn't take the problem really seriously."