A German man on trial for being a member of the extremist ISIS group once played for a Jewish soccer club.

Kreshnik Berisha, 20, went on trial in Frankfurt on Monday, in Germany’s first such case, the Associated Press reported. Berisha is alleged to have traveled to Syria where he fought with the group for five months before he returned to Germany.

Berisha, who reportedly comes from a Muslim family from Kosovo, was arrested in Germany in December on charges of membership in a foreign terrorist organization. He is believed to be one of about 400 German citizens who have joined jihadist groups fighting in Syria since the beginning of the more than three-year-long civil war.

He has since “turned his back” on ISIS, defense lawyer Mutlu Günal told the British newspaper The Guardian. The judge reportedly is working with prosecutors on a plea deal in exchange for information about the extremist group.

Berisha played on the under-17 youth team of Makkabi Frankfurt, a prominent Jewish soccer club, as recently as 2011, according to the AP. Membership in the team is not restricted to Jews and is described as diverse.