His testimony could very well have helped Germany's leading security officials glean vital information that could help track down other possible terrorists. But with Jaber al-Bakr's suicide, the most important source of such information has gone silent.

'Really Tired'

It's day three after the spectacular arrest in Leipzig and Mohamed, Sami and Ahmed are sitting in the apartment of a friend in a large German city. Worried that Islamists could take revenge on them in Leipzig, the three are in hiding and have declined to provide their full names. One of them doesn't even want his first name printed, so we have used the pseudonym "Ahmed." Nevertheless, they are eager to share their version of the story.

Are they proud or relieved? Mohamed, who worked as a hairdresser in Syria, shrugs his shoulders. "No," he says. "I'm just tired. Really tired." He has hardly slept since Sunday night, he says.

Too much has happened since then. He and his two friends have been celebrated in the German press as "the heroes from Leipzig." German Chancellor Angela Merkel has thanked them for their actions and politicians from a variety of parties have suggested they be given the Order of Merit, Germany's only federal decoration.

The heroes themselves are less effusive. "We only did our duty," says Sami.

More than anything, they want to counter the accusation made by al-Bakr before he committed suicide. The terror suspect told Leipzig police that, far from being heroes, the three were accomplices who had supported his plot. Security officials, though, say that the three have not been connected to any of the preparations al-Bakr made prior to his arrest. By the time SPIEGEL went to print on Thursday night, officials continued to view the three as witnesses and not as suspects.

"Al-Bakr is crazy," Ahmed says angrily. "He wanted to kill us too. We had absolutely nothing to do with him."

After the two attacks this summer -- one in Würzburg, which saw a 17-year-old Islamist from Afghanistan attack train passengers with an axe, injuring five, and another in Ansbach, where a Syrian refugee blew himself up, injuring 15 people -- many in Germany have begun seeing refugees as potential terrorists. The case of al-Bakr in Chemnitz has further confirmed such suspicions. But the three men from Leipzig would like to change these impressions and show that the vast majority of Syrians in Germany are, like them, interested only in the safety and peace their host country has provided them.

A Mysterious Phone Call

Thirty-six years old Mohamed A. is a sturdily built man with shoulder-length, black hair with a fear of dogs. He has a wife and five children who remained behind in Syria. Ahmed E. is 28 years old and his family -- wife and three children -- is likewise still in Syria. He wears a goatee and has black curly hair. In Syria, he studied mechanical engineering and now dreams of being able to continue his studies here in Germany. Sami M. is 26 years old and used to work as a truck driver. He is a big fan of FC Bayern München.

All three are from the same city in Syria and came to Germany last summer and fall by way of Turkey, Greece and the Balkans. Some of their statements are contradictory and others are difficult to confirm, but on the whole, the story they have to tell seems credible.

Mohamed says he was invited to dinner on the evening of Saturday, October 8 by a Syrian acquaintance in Leipzig and brought along Sami, who was visiting from Stuttgart. At around 6 p.m., his phone rang. According to the story told by the three refugees, the Syrian caller introduced himself as Khaled and claimed that he had received Mohamed's number from a man at the train station. He said he was new in the city and needed a place to stay for one or two nights, even offering to pay. That telephone conversation is one aspect of the story in which investigators are particularly interested.

Mohamed asked Sami to pick up the visitor at the Torgauer Platz tram stop, not far from Leipzig central station. As would later become clear, the visitor was not actually named Khaled, but Jaber al-Bakr. Sami recalls that the man seemed confused -- his clothes were dirty and his hair mussed. "I pitied him," he says. The men offered their guest lamb with rice and al-Bakr ate ravenously, they say, telling them that he hadn't eaten the whole day.

After eating, Mohamed took Sami and al-Bakr back to his apartment in a complex in the Paunsdorf neighborhood of eastern Leipzig. Later that evening, Ahmed joined them. The four of them sat together in the kitchen drinking tea and talking about Syria and life in Germany. Al-Bakr said that he wanted to find a job in Leipzig. Because he didn't have any clean clothes, Mohamed loaned him clothes to sleep in.

Didn't they have reservations about taking in a man that none of them knew? Mohamed raises his eyebrows and sticks out his lower lip. "I didn't think about it too much," he says.

Mohamed spent three months in a refugee hostel in Munich before moving to Leipzig. In the hostel, he slept in a hall and shared a shower with dozens of people. Ahmed, for his part, stood in line every night for several weeks in Berlin to register as a refugee. "It's completely normal for us to help a compatriot in need," they say. What the three didn't know, however, was that their guest, who they still considered to be harmless, was wanted by the Saxony authorities, who had lost track of his whereabouts.

The initial attempt to arrest al-Bakr had actually been well prepared. Domestic intelligence officials had received indications of a Syrian terror suspect in mid-September and intelligence agents secured assistance from officials in the states of Brandenburg and Saxony-Anhalt to monitor the residential building at Usti nad Labem Street 97. The communist-style concrete block building was one of many such structures in the quarter, an area which housed 90,000 people during East German times.

Al-Bakr was monitored there until intelligence officials notified the Saxony police last Friday. The police quickly assembled a specialized team and turned up at the site at 9:45 p.m.

They staked out the building throughout the night until a man emerged at 7:04 a.m. An "unidentified person," according to an internal report, "hastily left the target object" heading for the Chemnitz city center. Officers fired a warning shot, but the man disappeared.

The state criminal police office says the officers weren't totally sure it was al-Bakr and that it was impossible to shoot at him because there were innocent bystanders in the field of fire. A pursuit on foot likewise failed: The officers were wearing protection weighing 30 kilograms (65 pounds).

The account raises questions. How could a man wearing a backpack, a person suspected of preparing an imminent bomb attack, be allowed to simply run away? Because the officers were wearing heavy equipment?

Experienced officers who have been part of such operations in the past are astonished by this version of events. "Such operations are always prepared with the assumption that something won't go as planned," says a former member of a state police special operations unit. "Something can always go wrong. That's part of it. But it's unacceptable that a suspect can simply run away and isn't even followed."

'As Short as Possible'

The failures seemingly didn't stop there. According to internal Saxony state documents, a person "identical" to the man who fled later returned to the building, leading police to believe that the suspect was back. Officers raided the building, breaking down more than 30 doors as they searched the entire complex. A spokesman for the Saxony criminal police force would later say the raid was "nevertheless a successful part of the operation."

Still, there was no sign of al-Bakr.

Even as a Europe-wide search for the Chemnitz suspect was underway, Mohamed, Ahmed and Sami were chatting cluelessly with their guest on Sunday morning in Leipzig.

Al-Bakr asked them where he could get his hair cut. "How do you want it?" asked Mohamed. "As short as possible," al-Bakr replied, whereupon Mohamed retrieved a shaver from the bathroom. A short time later, at around 11 a.m., Mohamed, Ahmed and Sami left to go swimming and, afterwards, to visit a friend. Saying he was tired, al-Bakr stayed behind in the apartment.

Until just a few years ago, there were just 200 Syrians living in Leipzig. But since the outbreak of the civil war, that number has risen to 5,000. Most Syrian refugees tend to associate largely with other Syrians and Ahmed says it isn't easy to establish contacts with German residents of the city. He knew nothing of Islamophobic demonstrations and had never heard the word Pegida, the Dresden-based anti-immigration organization that has been staging anti-Islam marches in German cities since the fall of 2014. Nevertheless, Ahmed sensed the hostility of people in Saxony, saying that neighbors would slam their doors shut when they see them. Ahmed and Mohamed avoid public places and spend most of their time at home or at the homes of other refugees.

Throughout Sunday, news of the planned terror attack flooded television and radio broadcasters in Germany, but Mohamed, Ahmed and Sami initially took no note, instead playing cards in their friend's apartment. It was only later that evening that Ahmed looked at his Facebook page on his mobile phone. He noticed a story about the planned terror attack in Germany and clicked on a photo of the suspect.

Tied Up with a Power Cord

What he saw made him dizzy. The man in the photo looked exactly like the guest staying in Mohamed's apartment. "That can't be," Mohamed said. The Syrians looked at more photos until they no longer had any doubts that the man who introduced himself as Khaled was actually Jaber al-Bakr.

The Leipzig-Südwest police station was only sparsely manned shortly before midnight on Sunday night and initially Ahmed and Sami found only a single officer on duty. Ahmed had only been studying German for a few months and he struggled mightily as he tried to explain to the female officer what had taken place in his friend Mohamed's apartment. He was unable to string the words "terrorist," "house" and "help" together in a comprehensible sentence.

Just a few kilometers away, Mohamed, together with the friend with whom they had just been playing cards, slipped into his apartment. Al-Bakr had already gone to bed. Mohamed opened the backpack belonging to the terror suspect and found a combat knife and cash. He took a deep breath and then he and his friend rushed their guest. Al-Bakr tried to fight them off and yelled, but the two Syrians were able to tie him up with a power cord.

In our interview, Mohamed acts out the scene with his hands. "It was actually quite easy," he says.

Al-Bakr offered his captors money if they let him go, telling them that he had received 10,000 euros to carry out the attack. "You can have as much as you want," al-Bakr told them. Mohamed rejected the offer. "The guy was a terrorist," he says. "We fled Syria because of people like him. For us, turning him into the police was the obvious thing to do."

The two Syrians in the apartment in Paunsdorf then sent a picture via WhatsApp of the tied-up al-Bakr to Ahmed, who showed it to the police. Suddenly, they were able to understand the urgency of the situation and called for backup. Half an hour later, the police sped into the eastern Leipzig neighborhood and stormed the apartment. The Syrians were interrogated for several hours that night and were allowed to go only on Monday morning. They were interrogated again -- in a different state -- on Thursday.

But what about the man who had been plotting the attack? In an effort to find out more about him, SPIEGEL contacted his brother Alaa, who is 10 years older, by telephone. He lives in Saasaa, a town not far from Damascus, with his parents, three sisters and four brothers. Their father is a prosperous building contractor who is loyal to the regime and has contacts to Syrian President Bashar Assad's Baath party.

Jaber, he said, had been a normal youth. He had loved karate and he prayed and fasted, but he hadn't been a radical. He didn't have a girlfriend and had been in his third year at the University of Damascus, where he studied the new discipline of mechatronics, a combination of mechanical engineering and electronics. He had been temporarily detained by the police because he criticized Assad at the university.

Prior to fleeing Syria in November 2014, Jaber allegedly stole 5 million Syrian pounds, worth around 24,000 euros at the time, from his father. He used the money for his journey to North Africa, where he boarded a boat for Italy and then headed onward to Germany. At that time, his brother said, Jaber al-Bakr was not politically engaged, adding that he was recognized as a refugee in Germany after just a few months and began learning German.

Alaa regularly spoke to Jaber on the phone. He says: "My brother was radicalized in Germany." Jaber, he says, watched horrific videos from Syria in the internet and an imam in Berlin brainwashed him, telling Jaber to return to Syria and fight. In September 2015, he says, al-Bakr traveled via Istanbul to the Islamic State stronghold of Raqqa to join the extremist group.

He informed his family that he was now fighting for IS. Alaa tried to talk him out of it, saying that no matter what he wanted politically, he should never, never join the "Islamic State", but Jaber answered that the only independent power in Syria was Islamic State. Shortly thereafter, the family broke off contact. Jaber al-Bakr returned to Germany, but his brother says he doesn't know when, exactly. "At some point in the last two months."

Blanket Denial

The two haven't spoken to each other since August. At home in Saasaa, Alaa al-Bakr doesn't believe the horrific end of his brother's story. "I raised my brother. He would never have carried out an attack! That's a lie!" Alaa believes that the German police murdered Jaber and refuses to believe that his brother killed himself -- that he hanged himself in Saxony, far away from his hometown of Saasaa.

At 12:42 a.m. on Monday, police arrested Jaber al-Bakr, who had been tied up by Ahmed and Sami. According to investigators, he was interrogated by officers of the Saxony state criminal police office -- without a lawyer present -- four "around two hours" the next morning with the help of an Arabic-language interpreter.

He denied all of the accusations against him, accusing others instead: the man who had given him the apartment in Chemnitz and the three Syrians who had turned him into the police the night before. After the interrogation, at around 1:30 p.m., the arrest warrant was presented, again in the presence of a translator. During the official presentation of the arrest warrant, the accused "said nothing further," investigators say. It took just 15 minutes.

That afternoon, police brought al-Bakr to the Leipzig prison, where there was no interpreter. His lawyer Alexander Hübner says al-Bakr didn't understand any German and that it was impossible to communicate with him without a translator present. The prison warden spoke of "communication difficulties," but added that the prisoner seemed calm and focused. The judge who authorized his imprisonment warned of the potential for a suicide attempt but also identified al-Bakr as a potential danger to other prisoners or prison staff.

Al-Bakr was issued a T-shirt and jogging pants, the kind of prison clothing given to all prisoners in pre-trial custody in Leipzig. Because of the suicide risk, it was agreed that he would be checked on every 15 minutes. Because of the dangers he potentially presented to others, the Syrian was placed in isolation. Normally, prisoners at risk of committing suicide aren't left alone, but judiciary officials did not identify an acute danger -- at least not on the basis of his gestures and behavior. With no interpreter present, nobody could understand him.

One day later al-Bakr had an appointment with his lawyer, Hübner, who brought an interpreter along with him from Dresden. They didn't have a detailed discussion but Hübner said his client seemed stable, but he noticed that al-Bakr refused to consume any food and didn't want to drink anything either. "That made it clear that my client was putting his life on the line," says Hübner.

Peculiar Behavior

After meeting with the lawyer, the high-profile new arrival spoke with the institution psychologist using an interpreter. The psychologist found al-Bakr to be calm and withdrawn. She said that he asked questions about his imprisonment and wanted to know if he was at greater risk of deportation because of his hunger strike. This was seen as a sign that al-Bakr was thinking of his future, which didn't suggest that he was planning to commit suicide. The psychologist concluded that there was no acute danger of suicide and that his cell didn't need to be inspected every 15 minutes any more. Every 30 minutes was sufficient. According to the warden, it was a group decision. The supervisory authority in the state justice ministry also accepted this conclusion.

At 5:50 p.m. that same day, though, al-Bakr began exhibiting peculiar behavior: He climbed onto his bed and tore down the ceiling lamp. It was later discovered that an electrical plug had also been torn out in the cell. The officers believed it to be vandalism, which, they say, isn't uncommon among agitated new arrivals. And yet, they had found al-Bakr to be rather calm. Was this, perhaps, an initial attempt to kill himself?

That night, there was no electricity in al-Bakr's cell, repairs having to wait until the next day. The idea of bringing the inmate to a secure suicide-proof cell wasn't discussed. "There was nothing to suggest an acute danger," the warden says.

Hübner called the prison on Wednesday afternoon to speak with them about the problem of the hunger strike and al-Bakr's refusal to drink. Hübner was told that there was a water faucet in the cell and that nobody dies of thirst when water is available. They also discussed the lamp and the electrical socket. Finally it was agreed that close attention would be paid to the inmate "because of the overall circumstances." The lawyer was assured that al-Bakr was being regularly supervised.

By Wednesday night, it was too late. The last regular inspection of the cell took place at 7:30 p.m., at which point al-Bakr was seen alive. At 7:45 p.m., 15 minutes earlier than scheduled, a trainee went to the cell and found the inmate dead at the grate, asphyxiated by his prison-issue T-shirt. Help came too late and at 8:15 p.m., the terror suspect was declared dead.

Saxony's Justice Minister Sebastian Gemkow, a member of Chancellor Angela Merkel's Christian Democrats (CDU), says that the Saxony judiciary did everything it could to prevent the suicide. The prognoses of the psychologist, he said, had unfortunately not turned out to be correct. He said that the decisions made at the prison were "reasonable."

But al-Bakr's lawyer, Alexander Hübner, believes that his client's suicide is indicative of a "clear failure" in Leipzig, triggered by the psychologist's misdiagnosis. The brief conversation she had with his client, he says, was insufficient for an adequate analysis. "Everything there simply went according to the pre-set formula."

But Jaber al-Bakr's suicide is much more than merely a failure of the Saxony judiciary. Al-Bakr's death is also a serious setback for the German intelligence agencies, which are trying to identify possible connections underlying the terror that has seemed to edge ever closer over the last several months. Al-Bakr may have had insights into terrorist networks, principals or modes of communication -- insights that are badly needed because, despite the authorities' best efforts, they still know precious little about the threat level facing Germany this fall.

Würzburg, Ansbach, Düsseldorf, Schleswig-Holstein, Chemnitz: In the public perception, Islamic State has long been spinning its web across the country. Spectacular raids in the last few months have strengthened the impression that Germany has, on several occasions, only barely escaped cataclysmic attacks. But as it turns out, the distinctions between terror-plots, empty boasting and false alarms are fluid.

And since with every real or suspected threat the number of tips expands, it is becoming more difficult for the authorities to keep up. By early October, the Federal Criminal Police Office (BKA) alone had received 445 reports in which refugees were described as terrorists or sympathizers. In 80 of these cases, the BKA launched investigations, while the majority of the remaining cases were mistakes or denunciations. German citizens have called the BfV's hotline 800 times since the start of the year. On top of this, the German Federal Intelligence Service receives an average of two warnings a week, though they sometimes come daily, from foreign intelligence agencies. Sometimes these are vague indications that a terror group intends to travel to Germany through Bulgaria in order to carry out an attack. But how should one act on such information?

The authorities are playing a losing game. If they ignore a semi-concrete tip and a bomb explodes afterwards, they seem unreliable. If they strike hastily and the suspects turn out to be innocent, they are accused of creating a climate of fear. "The pressure is enormous," says an experienced investigator, especially since the Paris attack. Since then, the margin of discretion has become smaller and smaller. The authorities now take every threat even more seriously.

The example of the four men who were targeted by investigators after a large raid in February -- and have since been described as a "Berlin IS cell" in the media and parts of the security apparatus -- shows where that can lead. They had supposedly planned an attack on Checkpoint Charlie and newspaper headlines proclaimed: "Capital in Crosshairs." The suspects had aroused the suspicions of the Federal Office for the Protection of the Constitution after a tip from a foreign intelligence agency in late 2015. Now the Berlin public prosecutor's office no longer believes it was an Islamic State cell. Three of the four suspects have since been deported to Algeria for a variety of infractions and it's possible that they belonged to a migrant smuggling operation. The fourth will soon be prosecuted for financing terrorism because he supposedly transferred money to Islamic State, allegedly for night-vision devices. But investigators didn't find any evidence that an attack was being planned.

Reasons for Doubt

But when the authorities don't find anything, does it mean that there was nothing there to find?

Even today, authorities are still shocked about the man who handed them the so-called Düsseldorf IS cell on a silver platter, a Syrian man named Saleh A. On the morning of February 1, he strolled into a police station in Paris' 18th Arrondissement and gave a thorough confession to the perplexed officers. According to Saleh A., he was the leader of an IS sleeper cell that was planning an attack on Düsseldorf's old town. He also passed along the names of his three supposed co-conspirators, all of whom have been in pre-trial detention since June 2. Saleh A. was recently extradited to Germany.

The news of a terror attack in the heart of the Rhineland generated a lot of attention, but there are reasons to be skeptical. One of the four, for instance, had a lifestyle that doesn't exactly fit with that of a fanatical Islamist: He had a German girlfriend, took drugs, drank alcohol and spent many of his nights in the club. Saleh A.'s claims that he "made a U-turn" overnight and went over to the good side are also suspect.

Another potentially serious reason to doubt the story is that another accomplice, whom Saleh A. claims to have met in 2014 with Islamic State in Syria, apparently was registered as a driver for a unit of the Algerian military that took part in anti-terrorism missions. That, at least, is what documents found by his defense lawyer, Marvin Schroth, show. As a member of the military, Schroth claims, his client could not have left his country.

Does that clear the suspects of wrongdoing? Maybe. But there is also incriminating evidence, like the fact that three of the refugees accused by Saleh A. came to Europe via the same route as the Paris attackers. The same is true of the three refugees who were recently arrested in Schleswig-Holstein. They and Saleh A. supposedly had contact to the same Islamic State group. The fact that they behaved unremarkably during months of observation could mean anything: that they don't have any nefarious intentions -- or that they had learned how to communicate in secret.

The authorities are carrying out tough, frustrating work. The same is true of the Federal Prosecutor's Office, which is currently working on over 140 proceedings against alleged Islamist terrorists or violators of international law in connection with Syria or Iraq. The federal prosecutors are keeping tabs on 700 further incidents of a similar nature. And with every new unresolved case, the pressure grows. Did the 16-year-old male refugee who was arrested in Cologne have similar plans to the axe attacker in Würzburg? One of his chat partners advised him to buy lots of matches to obtain sulfur for the building of a bomb, but no matches were found in his room. Did the woman who set off the terror alarm at the Frankfurt airport do so by mistake or intentionally? And is it a coincidence that she came "from the Arab region"?

Just One Wish

Almost nothing is as it seems in the shadow fight against terrorism. Many, though, have gained the impression that Islamic State is everywhere. And since the opposite is hard to prove, an experienced investigator of the state security apparatus says: "Nobody can square it with their conscience not to have prevented an impending attack." An ultimately unjustified intervention may be extremely frustrating -- "but as a trade-off, more tolerable."

Measuring the risk becomes more difficult as the political debate heats up. After al-Bakr's arrest, politicians from the Christian Social Union (CSU), the Bavarian sister party to Merkel's CDU, requested that the intelligence services receive immediate access to the personal data of all asylum applicants. CSU General Secretary Andreas Scheuer has demanded the "total revision" of the refugee registration process.

German Interior Minister Thomas de Maiziere found the CSU demands perplexing, because since a change to the law made in February, intelligence agencies have been able to access a newly created databank to clear up their security concerns. The system, to be sure, doesn't yet work perfectly from a technical standpoint, but it is expected that data-sharing will work seamlessly by the end of the year.

That, however, isn't enough to fix a further shortcoming: For over a year, Germany's Federal Office for Migration and Refugees did not hold hearings for most applicants from Syria. To ease the workload of migration officials, asylum applicants from the country were merely required to fill out a 10-page questionnaire. Experts warned that the accelerated process raised potential security issues. The questionnaire asked applicants whether they were part of the military or of an armed group in Syria, but what Islamist would answer "yes"?

Al-Bakr also had to fill out a questionnaire when he applied for asylum in Germany in February 2015. There was nothing in his answers that would have aroused security concerns. On June 9, he was recognized as a refugee. At the time, his fingerprints were compared with the databases of the intelligence agencies, but there were no matches.

The three Syrians from Leipzig, meanwhile, are wondering what will happen next. During our interview, Mohamed buries his face in his hands. He says he can't get the images of al-Bakr out of his mind and the Syrians don't want to return to Leipzig under any circumstances. "We just don't feel safe there," says Ahmed. He laughs sheepishly when told that many people in Germany consider him to be a hero. He doesn't want a decoration, as German politicians have proposed.

Ahmed, Mohamed and Sami actually only have one wish: They would like to get their families out of Syria -- and bring them to Germany.

By Jörg Diehl, Hubert Gude, Frank Hornig, Martin Knobbe, Ludwig Krause, Maximilian Popp, Christoph Reuter, Sven Röbel, Jörg Schindler, Fidelius Schmid, Andreas Ulrich, Andreas Wassermann, Wolf Wiedmann-Schmidt and Steffen Winter