An Iranian man arrested in western Germany earlier this year after a tip from U.S. officials has been charged with plotting an Islamist attack using ricin or cyanide, German prosecutors said Wednesday.

The 26-year-old, identified only as J.J. in line with Germany’s privacy rules, was arrested in January along with his brother in Castrop-Rauxel, a city in the industrial Ruhr region.

Prosecutors in Duesseldorf said he was charged with preparing a serious act of violence and terror financing. An indictment was filed in the state court in Dortmund.

A case against the suspect’s 32-year-old brother, who initially was suspected of involvement in the plot, was dropped for lack of sufficient evidence, prosecutors said.

They said the younger man had decided by the end of October to carry out an attack in line with the ideology of the Islamic State group by spreading ricin or a cyanide compound, and intended to kill as many people as possible by spreading the chemicals.

Even small amounts of ricin, which is produced from the seeds of castor oil plants, can kill an adult if eaten, injected or inhaled.

The Duesseldorf prosecutors didn’t say if there was an intended target.

The suspect is alleged to have been in contact via messaging services with extremists who gave him instructions on how to make the toxins. He is also accused of acquiring substances needed to make them.

Authorities said at the time of his arrest that information from authorities in the United States led to the operation, but they didn’t elaborate.

It will be up to the court in Dortmund to decide whether and when to send the case to trial.

(AP)