The article is in German (Google translation)In the days before the riot there were tensions between an Afghan convert to Christianity and Muslims. No Muslim was willing to Share a room with the Christian. The Christian was also 'mobbed' by the Muslims during daytime, though the article doesn't give any specifics. Given that the Afghan committed a death penalty offense under Sharia I wouldn't be surprised if his life was threatened.
On the evening of August 19th there was a heated argument between the Christian convert and Syrian Muslims. The convert tore a page out of a Koran and flushed it down the toilet. No information re the ownership of the Koran is given.
The lynch mob then chased the convert who found refuge in a guard's office.
Syrian, Afghan and Iraq Muslims formed the mob.