Abu Walaa and three other co-defendants are accused of recruiting fighters to send abroad to defend the terrorist militia’s self-declared caliphate.
Abu Walaa was a preacher at an infamous mosque in the northern city of Hildesheim that attracted Islamists from across Germany but has since been forced to close due to a ban.
The prosecution is seeking a sentence of 11and a half years for Abu Walaa, and terms of between four and a half and 10 years for the other three.
Defence lawyers have pleaded for their acquittal or milder sentences.
The four men first went on trial in 2017 on charges of supporting Islamic State and being members of a terrorist organisation.
The prosecution’s case was partly based on testimony from a young man from the city of Gelsenkirchen.
He had fallen into Islamist circles as a youngster but later turned his back on Islamic State and began cooperating with the authorities.
Information from a key informant known as ‘Murat Cem’ or ‘VP01’ also played a role, although that man did not testify in the end due to an objection from the defence, who argued that he was unreliable and had himself incited attacks. (dpa/NAN)