Ten months after the deadly attack and beating of Jonny K. at Berlin's Alexanderplatz, a Berlin district court has sentenced the six perpetrators to prison.

Onur U., who the prosecution portrayed as the main offender behind the attack, was sentenced to four and a half years in juvenile detention for assault resulting in death. He was 19 years old at the time of the attack. The other defendants received prison sentences of up to two years and eight months.

After Jonny K. was killed, Onur U. fled Germany for Turkey, where he holds citizenship. Following a month-long legal tug-of-war, the country handed Onur U. over to the German judiciary in April.

Watch video 01:03 Verdict in Johnny K. trial

The presiding judge Helmut Schweckendieck said, "A tragedy unfolded in which a young man who just wanted to help lost his life for no reason."

Jonny K., a Thai-German student, was beaten so severely outside a bar in October 2012 that he died shortly afterwards of a brain hemorrhage in hospital. A friend of Jonny K.'s who was also seriously injured in the attack testified in the trial as a witness.

The case sparked outrage across Germany and triggered a national debate on youth violence.

The victim's sister, Tina K., appeared as a co-plaintiff (pictured right). After the death of her brother, the 28-year-old began campaigning publicly against violence.

hc/msh (Reuters, AFP, dpa)