Castrop-Rauxel

The 32-year-old suspect and his 25-year-old brother were detained on Saturday night in Castrop-Rauxel, in western Germany, following a tip from U.S. security officials.

On Monday, they said they have discovered that he used two garages in the back yard of a house in Castrop-Rauxel, and they also were being searched with help from analysts trained to deal with possible dangerous substances.

Police and prosecutors said the man and another person were detained overnight in the town of Castrop-Rauxel, northwest of Dortmund.

They raided the man's Castrop-Rauxel residence, in the Ruhr region, where they found the "toxic substances".

The premises of the suspect in the city of Castrop-Rauxel were searched as part of the investigation, according to a joint press release from the Duesseldorf public prosecutor's office and police in the cities of Recklinghausen and Muenster.