Amri and his accomplices did not have permanent residence, according to the police report on the stabbing. They were often observed on the drug scene: "For this reason an arrest warrant was requested." Had the public prosecutor known about Amri's criminal activities, he could have bundled the charges. A sentence of several years' imprisonment would have been possible. It wouldn't have taken terrorism to get Amri off the street. But the prosecutor didn't know Amri's prehistory, and witnesses chose to be silent. An arrest warrant was not requested, contrary to the police's proposal. Amri remained free.

In the days after the stabbing, Amri telephoned several times with his family. He sounded downbeat, and told them that he wanted to leave Germany. Apparently this had to do with drug scene disputes: The cocktail bar is, according to a witness, owned by a large Arab family. Such an attack doesn't go unpunished. Amri was afraid, says a detective. And so the Tunisian bid farewell to his friends in Berlin and on July 29, 2016, jumped on a long-distance bus to Zurich.

But the investigators, who were still monitoring his mobile phone, knew his plans. In Friedrichshafen, just before the Swiss border, Amri was arrested. He has two fake Italian passports, 281.42 Euros in cash, his Samsung cell phone, and a joint.

Amri wanted to leave Germany. But Germany, which wanted to get rid of him, did not let him go. Unlike the Italians, the Germans opted for the moral solution: they didn't want to stick the neighboring countries with a potential terrorist, say ZEIT investigators. And then, when he was taken back to Berlin, Amri made his decision.

A deadly decision

In the autumn of 2016, the investigators note that noise in the Islamist scene picks up: suspicious sentences in conversations, cryptic entries on Internet forums. IS was calling for attacks in Germany, especially via the Telegram chat app. Some of the messages presumably came from the crowd around Abu Walaa, the Iraqi preacher who Amri joined in Hildesheim. Coincidence?

In September, potential assassins received an e-mail address on a German Telegram channel to send their "Bai'a," the loyalty oath of the IS, and its "Caliph" Abu Bakr al-Bagdadi. "Take care of your safety, and send this just before the operation," it said. Everyone involved with Jihadism in the security agencies could feel that something was going to happen. The question was when and where the lightning was going to strike.

In November, the IS magazine Rumiyah, distributed via Telegram, contained instructions for attacks with trucks: "Vehicles are like knives, extremely easy to get." Because they are not usually noticed, they are a means for anyone who can drive to commit "righteous terror" and "kill large numbers of unbelievers."

Anis Amri followed the instructions, at least in part. Before his attack, he made a video in which he swore loyalty to IS and his Caliph. He stood on the Kiel Bridge in Berlin's district of Moabit and recorded a "message to the crusaders" on his cell phone: The Muslims were going to come and slaughter "the pigs."

The almost three-minute-long video, which IS published after the attack via Telegram, is certainly irritating. For one thing, Amri is wearing headphones and gazing at the sky, as if he were listening. Is someone dictating the text to him at this moment? Moreover,  the video was not recorded just prior to the act. The trees still have green leaves. An analysis of the mobile phone revealed that the video was recorded on October 31 or November 1, 2016.

For almost six weeks after he made the decision to strike, Anis Amri was still moving around in Berlin.

There has been much speculation over the psyche of assassins. There is the moment when the diabolic wins the upper hand, in which a man is ready to kill, to sacrifice his own life for a supposedly greater cause. For Anis Amri, this point is reached in September or October 2016.

The investigators notice nothing.

Even worse, as the level of buzz around Amri rose, he disappeared from before the authorities' eyes. From September on, neither the Berliners nor North Rhine-Westphalia knew where he was, not to mention the BKA. In the GTAZ meetings, Amri was only a name on a list.

In the weeks before the attack, two different opinions existed within the relevant authorities: some investigators believed that Amri had dropped his attack plans, because he did not take part in the morning prayer or ritual slaughter, and because he took drugs. The other faction worried that the worst could transpire. Amri and his friends in the Berlin Fussilet Mosque showed a "group-dynamic increase in violent behavior." They believed that there was the danger that he had "descended into the underground," according to a Berlin LKA memo.

And this was what happened. Amri removed himself from the drug scene. He now lived halal, or mostly so. The investigators later found on his mobile phone a considerable collection of porn movies. The access logs show that he stopped watching them in October. One might say that he was disciplining himself in preparation for the final act.

The German authorities get an unexpected last chanceOn September 19, the Moroccan intelligence service DGST reported to the BKA, sending two photos of Amri. In one, he is a teenager standing on a square, presumably in Tunisia. The other, more recent photo, showed him with beard and head scarf. The islamonaute tunisia, as the Moroccans called Amri, had "joined IS," the communique stated. He has a plan, it stated, about which he will not issue any further details." Amri wanted "to join IS in Syrian-Iraqi territory or in Libya."

Four weeks later, the DGST wrote again. The Moroccans sent the Germans a new cell number for Amri, whom they noted was "in contact with jihad aspirants who were loyal to IS."

Attached to the letter were copies of photos showing Amri and his friends, a Russian Islamist, a German-Moroccan who poses with an ax, fighters with the black flag of IS, and an alleged cousin of Amri with a pistol. Pictures from the poetry album of Jihad.

The Moroccans wrote four times, the last time on October 17, 2016: "His current accommodation in Berlin is with a Moroccan follower of Jabhat al-Nusra," a branch of Al Qaeda. And they even deliver the clueless Germans the name of his roommates: Toufik N., a grim-looking man who, at a later point, will slam the door in the face of ZEIT reporters.

The documents were not a warning but inquiries on behalf of the Moroccans, say German authorities today, justifying why they paid no particular attention to the tips.

In fact, the Moroccans, who apparently ran their own intelligence operation in Berlin, make it clear in the letter that they consider the group around Amri to be dangerous, a cell of violent Islamists. With this information from the Moroccans, the Germans could have located the Amri in the decisive phase of his preparations. The Federal Office for the Protection of the Constitution, at a meeting of the GTAZ on November 2, 2016, was commissioned to follow up on the latest report with the Moroccans. However, the agency did not do it.

The Assault at Breitscheidplatz

On the evening before the attack, a Sunday, Amri met for the last time with his best friend. The man is called Bilal Ben Ammar, one of the Tunisians with whom Amri travelled from Italy to Germany. Ben Ammar is also considered an IS supporter, whom the Public Prosecutor General in Berlin had already investigated.

At 21:08, the two entered the Arab restaurant Ya Hala in Berlin's Wedding district. They sat down at one of the wooden tables in the back, meeting for about 20 minutes. What did they discuss that evening?

The next day, just hours before the attack, the friends phoned again at 2:30 pm, according to Amri's mobile phone records. How likely is it that Ben Ammar did not know about the attack?

Friedrich-Krause-Ufer is located along the Westhafen in Berlin, a narrow street between a canal and railroad tracks. Here trucks park regularly, often overnight. Amri knew the area, as the Fussilet mosque, where he prayed, is only a few hundred meters away. Amri was there once, on December 15. Witnesses watched him test whether one of the trucks was unlocked, without success. His mobile phone data confirms the statements.