An ISIS preacher in Germany, who was arrested last November, will go on trial on charges of radicalizing young people and running a militant network connected to the Berlin Christmas attacker.

Ahmad Abdulaziz Abdullah A., also known as Abu Walaa, will appear in court in the northern Germany city of Celle on Tuesday.

Abu Walaa, who is an Iraqi national, and four con-defenders are accused of supporting ISIS terrorist group, which is mainly active in Syria and Iraq but in recent years have conducted terrorist attacks in various countries.

According to the prosecutors, the five people were creating a pan-regional extremist militant network, let by Abu Walaa as ISIS’s representative in Germany.

“The goal of the network was to send people to IS (Daesh) in Syria or Iraq,” the prosecutors said in their indictment.

Abu Walaa’s social media followers once reached 25,000 in Facebook.

He is also called the “preacher without a face”, because of his concealed face in ISIS propaganda videos.

Before his arrest, the preacher was a regular speaker at events, the federal prosecutor’s office in Karlsruhe announced.

Germany’s government has announced that nearly 800 people left the country in 2015 for Iraq and Syria to join terrorist groups. However, it is not clear how many of them very motivated by hat preachers like Abu Walaa.