Ironically, Stasi agent Kurras soon became part of a special investigation group within "One," which the city government of Berlin had charged with searching for double agents among the ranks of the police. In a twist worthy of the plot for a spy novel -- and reflective of reality in 1960s West Berlin -- Kurras was put in the position of searching for his fellow East German agents.

"One" was a feared department. Even the members of other agencies within the police department viewed the men and methods of the special unit with a mixture of fascination and revulsion. "We may be looked at with suspicion," Kurras wrote, not without pride, in a report to his superior in 1965, "but we enjoy the greatest possible support from our police chief."

The members of "One" traded nicknames, calling each other names like "Bully," "Outlaw Star," "Pussy" and "Banana." Kurras's nickname was "Gendarme," and the department head's secretary was known simply as "Püppi."

One of Kurras's Stasi assignments was to come on to "Püppi" -- a job known as a Romeo assignment. After a few timid attempts, he reported that although he was not entirely averse to romancing "Püppi," he preferred not to be given such assignments unless "absolutely necessary." By way of explanation for his reticence, Kurras wrote that there hadn't been any real chemistry between him and "Püppi."

Kurras's strong points were his reliable reports, his attention to detail and his complete devotion to secret service. Beginning in 1955, and for the next 12 years, he supplied the Stasi with stellar espionage reports from West Berlin, all under the cover name "Otto Bohl." Thanks to Kurras, the Stasi knew practically everything that the police and state security agent in West Berlin were planning against the East Germans.

As an agent, Kurras provided detailed internal information about employees, personnel changes and the ways in which various agencies operated. He reported on birthday parties and discussions within a group of Social Democratic police officers, and he drew sketches of train stations and offices. Again and again, he provided his patrons in the East with top-secret information, such as data on East German defectors or tip-offs on planned searches of people suspected of espionage.

Kurras was paid for his services, earning a total of about 20,000 West German marks -- no small sum at the time. He learned the "Helin" secret code and, later, another code known as "Achim." He was given a radio and even wiretapping equipment to eavesdrop on his superiors. One set of microphones was intended for installation in the office of the head of the Tiergarten district criminal inspection division. Kurras set up a receiving station in his apartment. He used a Minox miniature camera, which he kept hidden behind a ledge in the hallway, to photograph official documents at night. He had made such a good impression as a zealous and industrious police officer that he was even permitted to take official documents home.

Kurras's superiors in the West also thought the world of him. During a personnel interview in 1964, he said that he was very interested in being "someplace where I can protect the government even more effectively." He asked for "even more important tasks, which will give me greater satisfaction, because I wish to show my strengths to my government even more." Beginning in 1965, Kurras was put in charge of intercepting Stasi radio communications.

Because having the perfect cover is part of an agent's life, Kurras, on the advice of the Stasi, joined the Social Democratic Party (SPD). At roughly the same time, on Jan. 16, 1964, he was accepted into the SED in East Berlin, after having been a candidate for membership for a long time. In his application for membership, Kurras had written that he wanted to devote his "full efforts to the party." His sponsor was a woman nicknamed "Lotti," his Stasi agent supervisor and an old communist born in 1901, who had worked for the secret intelligence service of the German Communist Party in Berlin in the 1930s. A resolute Stalinist, "Lotti," or Charlotte Müller, was a bit pudgy, earning her the nickname "Dumpling." She used visits to her sister Käthe in West Berlin's Spandau district as a subterfuge to meet with Kurras. The two would meet in an ordinary café they called "Trude," near a canal lock in the Tiergarten park. During these meetings, "Lotti" would also instruct Kurras on correct class consciousness, especially during his occasional lapses of enthusiasm, and, of course, would make sure that he was imbued with the necessary anti-fascist beliefs. She had been interned in the Ravensbrück concentration camp.

Even when Kurras went to Austria on vacation, he would make the occasional side trip to Czechoslovakia to meet with Stasi employees. While in Naples, he reported "fleet concentrations in the harbor" to his East Berlin contacts.

Kurras sometimes had trouble coping with his double role, especially when, in his West Berlin police uniform, he was called upon to treat his fellow East German agents harshly. As a valued member of "One," he was often brought in to interrogate captured East German agents. "Lotti" would often have to boost his spirits after these interrogations.

On Jan. 26, 1965, she wrote, in a report about a conversation she had had with Kurras: "He expressed certain doubts about having to help arrest people who are working for the German Democratic Republic. I replied that he should do his work properly, even when arrests are necessary, and I reminded him of Dr. Sorge, who also had to perform tasks that went against his convictions, in order to obtain important information." Her pep talk was apparently successful. A short time later, the agent supervisor wrote, clearly pleased with herself: "Bohl no longer has any reservations about being assigned to cases that involve suspects who work for the Ministry for State Security." By 1967, Agent Bohl had apparently lost his inhibitions to such a degree that he took part in a mission to search for Stasi "sleepers" in the West's police structures.

Kurras was literally inundated with work. The Stasi was constantly asking him for data on individuals and vehicles, and Erich Mielke, the head of the Stasi, used his zealous agent to gain access to practically all West Berlin police files, including wanted lists. In addition, Kurras, during short meetings in public restrooms, turned over Minox film or keys he had copied for safes and the doors of police offices. Of course, the Stasi was also extremely interested in information about individuals helping East Germans escape, possible escape tunnels or the Allies' underground shooting ranges.

Kurras worked off his stress by drinking and going to the shooting range. Within Stasi circles, Kurras was considered "an overachiever, but with a tendency to consume alcohol excessively." He was also "extremely enamored of weapons" and had "an excessive fondness for wearing uniforms and serving on the police force. During the course of our cooperation, he has made no secret of the fact that he is a fanatical devotee of marksmanship. He has also asked to obtain, from the Ministry for State Security, certain weapons that are very difficult to buy in the West. For example, he asked for a P 38."

Kurras was obsessed with weapons. He owned a large gun collection, and his performance at the shooting range was outstanding. He won several Berlin police force marksmanship competitions, and he spent "most of his free time at the shooting range," as one of his commanding officers in the East noted. His second job with the Stasi also helped pay for his hobby. He would spend up to 400 marks a month on ammunition alone. Even the password an unknown Stasi employee would use to contact him in West Berlin was significant: "Hello, Mr. Kurras, I am here to see you because of the shooting department."

After the Ohnesorg shooting, Stasi officials admitted in a June 8, 1967 internal memo that they had known about this "character weakness," but had underestimated it.

The shot that this member of the political police force fired at student demonstrator Benno Ohnesorg from his service pistol was to become a shot fired at many heads -- and the starting shot of Germany's student movement.

Until then, the Socialist German Student Union (SDS), with only about 200 members in Berlin, had campaigned for democratization at the so-called Ordinarienuniversität (a university controlled by tenured faculty) and had organized protests against the American war in Vietnam. The SDS was essentially a collection of well-behaved middle class offspring trying their hand at democracy.

When the Shah of Iran, Mohammed Reza Pahlavi, was expected for a state visit, the SDS activists in Berlin were initially unsure of whether to demonstrate against his regime's torture practices. An Iranian exile, journalist Ulrike Meinhof and Kommune 1, a politically motivated commune in Berlin, called for protests. The German Interior Ministry in Bonn, then the capital of West Germany, classified the Iranian dictator's visit as a Security Level I event.

On the morning of June 2, 1967, Persian secret agents and Shah supporters, soon to be referred to as "claqueurs," were assaulting demonstrators and bystanders in front of the Schöneberg Town Hall in West Berlin. The dictator and his wife, Farah Diba, were scheduled to attend a performance of Mozart's "Magic Flute" that evening. The commander of the security police, Hans-Ulrich Werner, was in charge of planning the police operation at the Deutsche Oper opera house. Werner had made his contribution to the Holocaust in World War II by "fighting partisans" in Ukraine. He had police barricades installed on the sidewalk across the street from the Opera, thereby creating a narrow path that was blocked off to the rear by a construction fence. By early evening, demonstrators and bystanders had crowded into this narrow gauntlet, which was only a few meters wide.

Shortly before 8 p.m., when the Mercedes 600 carrying the Shah and his wife pulled up to the Opera, the crowd's chants of "murderer, murderer!" grew louder, and tomatoes and a few colored eggs began flying through the air. The police grabbed Rainer Langhans, a member of Kommune 1 who had thrown the colored eggs, threw him into a police van and beat him up. The state guest disappeared into the Opera, and calm returned to the street.

'The Protesters Are a Sausage'

Nevertheless, the police launched a large-scale attack, without having instructed the demonstrators to clear the area first as was required. As journalist Sebastian Haffner wrote, the police "boxed in the demonstrators, crowded them together and then, with uninhibited brutality, used their nightsticks and boots on the defenseless demonstrators as they stumbled and tripped over each other."

The next day, Police President Erich Duensing used these words to explain the strategy: "Let us assume that the protesters are a sausage, you see. All we have to do is squeeze it in the middle, causing it to burst apart at both ends."

When the protesters who had managed to escape from this sausage-like enclosure attempted to run away, the police opened fire with a water cannon. Special undercover units, employing a strategy they called "hunting foxes," tried to catch the presumed ringleaders. The demonstrators, followed by the police, ran toward a parking lot underneath a building on a nearby street.

A young couple, Benno and Christa Ohnesorg, was standing at the next intersection. They had been married only six weeks and were expecting a child. They were shocked by the police violence. Benno Ohnesorg, a 26-year-old student of German and Romance Studies, wanted to find out what was happening in the parking lot. His wife, who felt the situation was too dangerous, said goodbye and went home.

Kurras was part of one of the attack units. He was wearing a grayish-blue uniform and carrying a 7.65- millimeter Walther PKK pistol. He too was headed for the parking lot, which had become a scene of chaos, with people screaming and running back and forth between parked cars. Three police officers kicked and clubbed a student lying on the ground. Ohnesorg was also beaten. Then Kurras fired his pistol, hitting Ohnesorg in the back of the head.

Later a judge, in explaining his decision to acquit Kurras, cited the strong suspicion "that Benno Ohnesorg was still being beaten as he was lying on the ground, mortally wounded." Eyewitnesses overhead a fellow policeman shouting at Kurras: "Are you crazy, shooting here?" Kurras replied: "My gun just went off." His commanding officer shouted: "Kurras, get to the back! Now! Get out of here!" At that point, at the very least, Kurras proved to be a professional. He managed to lose the magazine for his pistol and took his suit to the cleaners the next morning.

While the seriously wounded Ohnesorg lay on the ground, police officers prevented a Norwegian doctor from administering first aid. Medics did not take away Ohnesorg until 15 minutes after the gunshot to his head, and it took another 45 minutes before he arrived at a hospital. The fact that doctors there removed the piece of bone containing the gunshot wound from the top of his skull and then discarded it could not be seen as anything but an attempt to cover up the killing.

That night Heinrich Albertz, the city's mayor and a Social Democrat, announced: "The city has run out of patience." The newspapers, owned by the Axel Springer publishing house, used the same tone to drum up the public mood. "Those who produce terror," wrote the tabloid B.Z. in a grotesque inversion of events, "must expect harsh treatment." Bild accused the students of having used "SA methods" (a reference to Hitler's paramilitary storm troopers, the SA). Ohnesorg, the tabloid claimed, was "not the martyr of the Maoist student movement, but its victim."

The West Berlin city government imposed a general ban on protests throughout the "free section" of the city, and police laid siege to the campus of the Free University. In parting, the Shah gave Mayor Albertz a piece of friendly advice: "You have to shoot a lot more. Then things will return to normal here."

In addition to losing their faith in the police on June 2, 1967, most of the protesting students soon lost all confidence in the judicial system. Fritz Teufel of Kommune 1, who had been beaten by policemen in front of the Deutsche Oper, was accused of a serious breach of the peace. Only after two months and a solidarity hunger strike staged by students was he temporarily released from custody.

The deadly marksman Kurras, on the other hand, never spent a single day behind bars. The police union gave him 60,000 German marks so that he could hire a top attorney to defend him against charges of "negligent homicide."

In his testimony before a Berlin district court, Kurras said that he had been "knocked down and brutally beaten by 10 or 11 people." He claimed that two young men had threatened him with knives and that he had then fired a warning shot. In the ensuing melee, he said, he must have fired the fatal shot by accident. None of the eyewitnesses was able to corroborate even a portion of his version of the incident.

A psychologist who examined Kurras concluded that he was somewhat unstable but not excessively aggressive. For lack of evidence, the Berlin court acquitted the shooter. The verdict was upheld on appeal, and four years after the shooting he was allowed to rejoin the police force. Christian Ströbele, a Green Party member of the German parliament today, was one of the Ohnesorg family's joint plaintiffs at the time. "To this day," says Ströbele, an attorney, "I do not understand why Kurras was so consistently protected." Ströbele wants to see the case investigated to determine whether East German officials intervened on Kurras's behalf in West Berlin. He believes that if Kurras had been convicted, Germany would not have seen "such rapid radicalization among students."

Kurras inadvertently ensured that June 2, 1967 became the initial trigger of the student movement and the extra-parliamentary opposition. Within a few weeks, the Socialist German Student Union in West Berlin managed to increase its membership five times over, to about 1,000.

In the photo that became a contemporary historical icon of June 2, 1967, fellow student Friederike Dollinger kneels beside the mortally wounded Ohnesorg. "I thought I was staring into the face of fascism," she said later when reflecting on the experience. A fatal spiral of violence had begun.

In the late evening hours of June 2, 1967, angry demonstrators met at the SDS headquarters on the city's famous Kurfürstendamm boulevard to discuss the dramatic events of the evening. An agitated young woman called out: "This is the Auschwitz generation. It's impossible to talk to them." Some of the more levelheaded activists in the crowd rejected her suggestion to storm a police barracks and obtain weapons.

The young woman was Gudrun Ensslin, the daughter of a pastor. Hardly more than three years later, Ensslin, her friend Andreas Baader and Horst Mahler, an attorney who had represented the Ohnesorg family, were among the founders of the Red Army Faction (RAF). The terrorist group's ensuing crusade against the West German republic culminated in the 1977 series of events known as the German Autumn, and cost the lives of more than 50 people.

The second West German terrorist organization that emerged from the student movement called itself the Second of June Movement. The group kidnapped Peter Lorenz, a Berlin politician with the conservative Christian Democrats, in 1975.

When asked about the revelations concerning Kurras, former Second of June Movement member Till Meyer says that the history of June 2 should not be "rewritten by even the slightest amount. A West Berlin police officer who lost his cool fired the first shot at us." According to Meyer, it was something that neither the police leadership nor the Stasi would have wanted to happen.

Meyer's former comrade-in-arms Michael "Bommi" Baumann writes off Stasi agent Kurras as nothing but an embarrassing and grotesque relic of the Cold War for all parties involved. "An SED communist opens fire and kills a peaceful liberal, and the West Berlin police protect a Stasi man."

Is this true? Would nothing have changed if the students had known about Kurras's background?

The situation in West Germany in the late 1960s was such that many were simply waiting for an incident like Ohnesorg's death. Many university and high-school students perceived their country as something of a Wilhelmian authoritarian state, one in which the lowly citizen was already considered in violation of the law if he expressed public outrage over a police officer who had acted illegally. For them, it was a country where playing a guitar at an outdoor fountain was enough to trigger the deployment of police units.

In the early 1960s, students already raised suspicions by reading Marx, something a normal student assumed was banned. Two-thirds of all students described themselves as apolitical. Professors, in their academic gowns, ruled over their departments like feudal princes, and when students so much as complained, a professor could easily be overheard saying: "All of you belong in a concentration camp."

Political activity at universities was uncommon, except to commemorate the East German rebellion on June 17, 1953. Discussion panels critical of the US's Southeast Asia policies were banned, and Willy Brandt warned students who planned to demonstrate against the Vietnam war "that we Germans tend to play up our role as teachers in world politics." For the tabloid press, demonstrators were nothing but "rowdies" and "rabble-rousers," while the Frankfurter Allgemeine newspaper described the street protests of like-minded people as "the stupidest and most useless means of political involvement."

To distance themselves from a society that had more in common with their parents' lives than theirs, more and more West Germans moved into large abandoned apartments in West Berlin in the 1960s, and began to experiment with new ways of living together. They sat around in clubs, read Sartre and Camus, consumed Marcuse, Marx and Freud, listened to Bob Dylan and the Doors, drank red wine and rum-and-coke, swallowed drugs like the stimulant fenethylline and sleeping pills. They complained about the bad food in student cafeterias and the bombing of Hanoi. They brought down Eberhard Diepgen, the chairman of the Asta student association who had proposed organizing students into a "voluntary police reserve unit for times of crisis," they interrupted lectures dressed in police uniforms and they went to jail for their actions. They had their fun and they unnerved the powers that be.

'No Regrets'

Although the "assassination" of Ohnesorg and the Kurras trial contributed to the radicalization of some members of the left to the point of violence, the attempted assassination of student leader Rudi Dutschke, the Vietnam War, the emergency laws  and other events only reinforced the conviction that they were living in an unjust world and a semi-fascist West Germany.

The members of the 1968 protest movement saw themselves as the enforcers of the world's conscience, and as partisans of a new world order held together by peace, love and equality.

They lived in an ideal world and with the conviction that they were entitled to reinvent sex, education, housing, music and democracy. There was only one power that could prevent them from bringing their human experiment to a happy conclusion: capital.

In other words, a revolt, an uprising against the conditions they despised, was inevitable. Nevertheless, some elements of the protest movement would have been different if it had emerged that Kurras was a communist during the investigations at the time. The case against the shooter would probably have proceeded in a different direction, because the fellow police officers who protected him with their silence would have testified against him instead. He would have been convicted, and his conviction would have muted the anger of demonstrators. For many students in high schools and universities, the Kurras trial and acquittal was just one more reason to characterize the West German government as fascist. A different verdict would have changed their view of the government.

Some members of the German left would hardly have turned to East Germany and its West German Party, the German Communist Party (DKP).

But the Springer press would also have been unable to apply its simple but effective formula equating a protester with a communist and, therefore, a henchman of the East German government. The press could hardly have exploited the news that a communist had shot a liberal.

For Kurras, the deadly shot on the street Krumme Strasse spelled the end of his lucrative relationship with the Stasi. Although it remained in contact with its agent, it clearly did so merely in an effort to control the damage. "Destroy material immediately. Discontinue work for the time being," East Berlin radioed to Kurras on June 8. "Resume contact following conclusion of the investigations. We consider incident as highly regrettable accident." Kurras replied: "Understood in part. Everything destroyed. Meet at Trude. Now on 15th. Need money for attorney."

The file also contains an empty envelope, which contained a radio message sent on June 17. Kurras had radioed about 1,000 characters, an unusually long message, but the text was removed.

According to the file, it was not until nine years later, on March 24, 1976, that Kurras met with the Stasi in East Berlin again. Werner Eiserbeck, his supervising officer of many years, noted: "Kurras behaved as if the last meeting had happened only a few days ago." The Ohnesorg killer, since demoted to a motor vehicle tracing unit, wanted to know whether he could resume working for the Stasi. He told Eiserbeck that his career path was "no longer impaired by the incident," that he had since been promoted and expected to be appointed senior inspector soon. According to the Stasi officer's report, Kurras felt "blameless and had no regrets." He said that his life had been "threatened by radicals attacking him with knives." At the end of the meeting, Kurras said that since the Ohnesorg shooting, he had "lost old sponsors, but gained new ones." The man had become a liability for the Stasi, and his file was closed.

The party that Kurras had once worshipped so ardently also distanced itself from the hard-working informer. After the first trial against Kurras, the SED newspaper Neues Deutschland expressed outrage over the gunman who had served his party with sword and shield for years. "The Murderer Grins with Satisfaction," the paper wrote in November 1967 headline, noting that his acquittal was "one of the most egregious political justice scandals since the expansion of West Berlin into a front city of the Cold War." Neues Deutschland also had harsh words for Kurras's second acquittal in December 1970. The verdict, the paper wrote, shone "a telling light on the entire anti-democratic policy" of the West Berlin Senate.

After his suspension ended, Kurras never truly regained his footing with the police. He was transferred from Department I, the police intelligence unit, to the "normal" criminal investigation department. As the then Berlin Police Chief Klaus Hübner recalls, "an internal position" had to be found for him at the time.

The former police chief paints a picture of a "traumatized man." According to Hübner, Kurras was an "overwhelmed police officer" who "got the jitters" at a decisive moment, which explains why he shot Ohnesorg. After that, says Hübner, Kurras was "hardly capable of being reintegrated." His coworkers at the new unit, the manhunt database, "kept their distance from him, and Kurras kept his distance from them."

There was talk of alcohol problems. In the summer of 1971, Kurras was picked up on a park bench, drunk, carrying a knife and his service weapon in his briefcase. He was no longer authorized to carry the weapon. He was suspended a second time and eventually reinstated a second time.

Kurras hardly ever appears in public anymore, except on the anniversary of Benno Ohnesorg's death. In May 1977, a photojournalist with the German magazine Stern tracked down Kurras in Spandau. When the journalist reached for his camera, a scuffle ensued and Kurras shouted: "You were allowed to photograph me in the past. Thank God those days are gone."

Kurras somehow managed to drag himself along in the police department. When he retired in 1987, at the rank of a senior inspector, everyone with the Berlin police "was pleased to see him go" says former Police Chief Hübner.

Regret remains alien to Kurras's nature today. In December 2007, when a reporter asked him about his momentous act, he shouted: "A mistake? I should have stalled until the sparks flew, not just once, but five or six times. Anyone who attacks me is destroyed. End of story."

When a reporter with Tagesspiegel visited him recently at his apartment, he found an old man with thinning hair. "That must be Ströbele's doing," he said, when asked about the revelations over his Stasi file. He also said that he shot Benno Ohnesorg "for fun."

DIRK KURBJUWEIT, SVEN RÖBEL, MICHAEL SONTHEIMER, PETER WENSIERSKI