Ulm's Islamic Information Center has been under observation for years, amid suspicion it has harbored and recruited Islamic militants. Stuttgart prosecutors launched a formal investigation into the organization earlier this month, under allegations it tried to illegally bring foreigners into the country.
Police had searched the center's premises in September, confiscating documents that must still be analyzed, prosecutors spokeswoman Bettina Vetter said.
The searches came after anti-terrorist forces arrested Fritz Martin Gelowicz, 28, described as the leader of an Islamic Jihad Union terror cell and a native of Ulm, as well as two other alleged militants whom authorities say were plotting to bomb U.S. targets in Germany. Authorities have said they do not know of a direct link between the three suspects and the Islamic Information Center.
All three had trained in terrorist camps in Pakistan, prosecutors said, and the case has raised concerns in Germany about homegrown extremists linking up with foreign terror groups.