BERLIN – A German man charged with joining Islamic State forces in Syria last year went on trial in Frankfurt on Monday in the first such case in Germany.Police arrested 20-year-old Kreshnik Berisha, who was born in Germany to Kosovan parents, in December.Authorities charged him with membership in Islamic State between July and December 2013.As a teenager, Berisha played soccer for the Jewish team Makkabi Frankfurt. According to the Frankfurter Allgemeine Zeitung (FAZ), Islamic clerics radicalized him when he was 16. He is believed to have joined a radical Islamic group while studying construction engineering at a local vocational college.An uncle told FAZ that Islam played no role at home for Berisha while he was growing up.According to the prosecution, the defendant left Germany by bus with a group of other Islamists and traveled to Istanbul and then Syria. Prosecutors say he received weapons training, fulfilled guard and medical duties, and took part in a recruitment campaign near Aleppo in northern Syria. They also say he engaged in combat on three occasions.If convicted, Berisha could receive a 10-year prison sentence.According to German media reports, Islamic State paid him $65 a month and provided food and clothing.Also known as ISIS, Islamic State has captured swathes of territory in Syria and Iraq, declaring a caliphate, an Islamic state ruled under Shari’a, or Islamic religious law.Dressed in a black hooded jersey, black T-shirt and gray tracksuit trousers, Berisha smiled as he entered the courtroom.“You’re a very young man without a significant criminal record,” lead judge Thomas Sagebiel told him.“We consider giving you a chance to help us exercise leniency,” Sagebiel said. “It mostly depends on you.”Berisha’s lawyer, Mutlu Günal, told the court: “I would say the accused is suffering from post-traumatic stress,” having probably witnessed much civilian suffering.If Berisha cooperates with the prosecution in exchange for a lenient sentence, he could provide valuable insight into the inner workings of Islamic State.Thousands of Western volunteers have traveled to Syria and Iraq to join such militant Islamic groups. The trend has raised fears in Europe and the United States of attacks by returning fighters.Security authorities say about 400 German citizens have joined ISIS in Iraq and Syria and that about 40 have been killed, some in suicide attacks. More than 100 are believed to have returned home.Günal said his client did not plan to conduct terrorist attacks in Germany. Nevertheless, among the charges leveled against him are that he was planning such an attack.According to the Taz newspaper, a fellow football player from Makkabi Frankfurt – the largest Jewish football team in Germany – described Berisha as quiet and friendly. He said religion did not play a role in their relationship.“We were a diverse team,” the player said.Germany last week announced a ban on Islamic State, making ISIS propaganda, symbols and activities illegal. Austria said on Monday it planned a similar crackdown.Chancellor Angela Merkel has broken with Germany’s post-war policy of not sending arms to war zones and has begun to send weapons and equipment to Iraqi Kurds fighting the Islamists.Reuters contributed to this report.