The Salafist from Hesse in central Germany was being monitored by security services after being accused of grievous bodily harm against a TV camera crew.
But he still managed to leave the country despite being under investigation and wearing an electronic tag around his ankle, Report Mainz said on Tuesday.
The 24-year old, named as Hassan M. from Offenbach, belonged to a group of Salafists in the Rhineland who were were known to police and were suspected of wanting to travel to Syria to join jihadists.
Report Mainz said Hasan wore the electronic tag from December 2013 to May 1st 2014 when the signal stopped.
“He disappeared after that. We couldn’t watch him anymore,” authorities told Report Mainz.
He managed to escape on a fake passport and crossed the Greek-Turkish border, before travelling to Syria, Report Mainz said.
Green Party politician Omid Nouripour, who sits on the parliamentary foreign affairs committee, called Hassan M.'s flight a “scandal”.
“When someone who is under investigation simply travels to fight in Syria it is more than a mishap, it’s a scandal,” he said.
Wolfgang Bosbach, interior affairs spokesman for the CDU/CSU in parliament, described the escape as a “nightmare”.
Around 400 people from Germany are thought to have travelled to the Middle East to join jihadists.
Justice Minister Heiko Maas told Spiegel on Saturday that 200 suspects are being investigated in connection with Isis.
Germany made support for Isis illegal last month.
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