The video footage shows a young man on a subway platform being confronted by two others. The taller one looms over the victim, close to his face, then swings a bottle at his head. The victim falls to the ground, and the attacker, wearing a black jacket and dark pants, stomps on his head four times.

The assailant then steps back to do a little dance. When he goes back to stomp on the man's head again a bystander intervenes and holds him back.

The images were widely broadcast in Berlin following the attack at 3:30 a.m. on April 23. The victim, a 29-year-old craftsman identified as Markus P., suffered from head injuries, a broken nose, contusions and ongoing psychological trauma. Experts say the injuries would have been worse if the alleged attacker had not been wearing rubber-soled shoes.

The two teenagers accused of attacking the man, Torben P. and Nico A., are now standing trial in Berlin on charges of attempted manslaughter and grievous bodily harm. Their stories, especially that of Torben P., who turned himself in to police after seeing a broadcast of the surveillance video, have been covered heavily in the German press. In particular, journalists and observers have sought to understand the possible motivations of someone who seems to be an unlikely criminal -- an 18-year-old with two retired parents who has said he wants to study law.

At the start of his trial, Torben P. said he was ashamed of his actions. "I am shocked and appalled by myself," he said.

The case is one in a series of highly publicized attacks on public transportation over the last year in the German capital that have frightened the public and prompted local political parties on the right to make the safety of the city's train platforms and buses a campaign issue. The most recent attack was reported Sept. 8 at an U-Bahn station in the northwestern district of Wedding, in which a 57-year-old man was hit in the face by two men in their early twenties.

Subway Safety and Campaign Slogans

A judgment in the Friedrichstrasse case will be handed down Sept. 19 -- one day after Berliners go to the polls to elect their new crop of state officials. Under Germany's federal system, Berlin is its own state, and it has a state government that is currently led by a coalition of the center-left Social Democrats (SPD) and the far-left Left Party.

The local branch of Chancellor Angela Merkel's conservative Christian Democrats (CDU) was criticized this summer after using the image of another subway attack on campaign postcards handed out by candidates at various events.

In that Feb. 2011 incident, 30-year-old Marcel R. was attacked by four teenagers in the metro station in the eastern Berlin district of Lichtenberg. The painter was injured so severely that doctors had to put him in an artificial coma temporarily. He later had to re-learn how to sit, stand, speak and move his fingers. The trial for that case will begin Nov. 19 in Berlin.

After news broke that the CDU was using the image -- one of the attackers jumping at the victim with the word "Safe?" stamped across it in bold -- the victim's sister told a local Berlin newspaper that she was considering legal action against the party.

The postcards have since been recalled, and the local CDU has stopped using any images from violence on public transportation in its campaign, says Michael Gentsch, spokesman for the Berlin party.

Still, the party has posted billboards with a photo of its top candidate, Frank Henkel, along with figures that compare the number of police officers cut from the force by the current government with the number of crimes committed on the city's buses and trains.

"Naturally, it still is an issue as long as there are still attacks," Gentsch says.

A Positive Public Mood

Security has often been used as a campaign issue in Berlin in the past, says Nils Diederich, professor of political science at the Free University in Berlin. In West Berlin in the years before the fall of the Berlin Wall, the security threat came from outside. Now, it is local.

However, Diederich predicts that the issue will not have much traction in the election because of an overall positive mood in the city. No matter what public opinion polls might show about safety fears, he says, "some candidates will hope to cash in on it."

Far-right parties like the NPD, which earlier this month won 25 percent of the vote in some parts of the northeastern state of Mecklenburg-Western Pomerania, will not play a significant role in the Berlin election, Diederich says.

Die Freiheit, a right-wing party founded last year by René Stadtkewitz, who was expelled from the local Berlin CDU for inviting anti-Islam Dutch politician Geert Wilders to come speak in the city, has also honed in on the issue of subway violence.

One of the party's campaign posters shows a close-up of Stadtkewitz's face and bears the slogan: "So that you can get home safely."

After the well-publicized attacks in late winter and spring, Berlin Mayor Klaus Wowereit, the top candidate for the Social Democrats (SPD) in the state election, presented his own platform for more security at Berlin train stations. His plans include adding 200 police officers and lengthening the time video surveillance recordings are kept before being erased from 24 to 48 hours.

But "brutal attacks" are a bad campaign issue, says Berlin SPD spokeswoman Daniela Augenstein, because they are "too serious."

YouTube Exposure

Despite the severity of the recent attacks, the violence on public transportation in Berlin is down. In 2010, there were 4,529 reported cases of dangerous and serious injuries on the street, or in public places, including public transportation in Berlin, according to police statistics. That number dropped 13.9 percent from the year before.

Many similar cases involving violence in public transportation often go before the Berlin court, but receive less media attention, says Robert Bäumle, a spokesman for the state's justice department. The reason why the Torben P. case drew so much attention, he says, is because the video of the attack was so well-publicized on the news and through YouTube.

Attacks in Other German Cities

Violence on subways and buses has also made headlines in other German cities recently. On Sept. 5, unknown assailants in Hamburg beat a 23-year-old man at the local train station of Elbgaustrasse, punching him in the head and kicking him as he lay on the ground. The victim was transported to a local hospital with a broken nose and a concussion.

Two years ago, in Sept. 2009, the nation followed the story of Dominik Brunner , a 50-year-old businessman who died after protecting four school children from two teenagers who were bullying them for money on a Munich commuter train. In a case that shocked many Germans, the two teens hit Brunner 22 times for interfering. He died later in a hospital. One of the attackers was sentenced to nine years 10 months in a juvenile detention center, the other to seven years. Brunner was posthumously awarded the Federal Cross of Merit for civil courage by then-German President Horst Köhler.

The recent subway violence in Berlin has also spawned a debate over civil courage, after it was reported that several people witnessed the attacks but did not intervene. But in the case of Torben P., video surveillance shows the alleged attacker being pulled away from the victim by a bystander, a tourist visiting from Bavaria who was also injured as a result.

'Hard to Find the Right Words'

In its judgment, the Berlin court will decide if Torben P., who was 18 at the time of the alleged attack, is sentenced as an adult, with a penalty of up to 15 years in prison, or as a minor, with a 10-year maximum penalty. The fact that he appears intoxicated in the footage might also play a role in lowering his sentence due to a provision in local law.

On Sept. 8, prosecutors in the case recommended four years in juvenile detention for the defendant. But that recommendation is not binding, and the panel of judges on the case could rule otherwise in their Sept. 19 decision.