"Based on the existing data, there is a high probability that a terror attack has been thwarted here [in Cologne]," Maassen told the Rheinische Post newspaper.
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According to the newspaper, the police found a highly toxic substance ricin on Tuesday in a flat rented by 29-year-old Tunisian national. The man was detained on suspicion of producing a biological weapon and intention to commit a crime against the state, the newspaper added.
Maassen reportedly added that the intelligence service found out that the man could be involved in the production of a toxic agent, detected his name and address and referred the information to the police.