Sief Allah H., whose last name wasn't given in line with German privacy laws, was taken into custody Tuesday during a raid on his apartment in Cologne.
Authorities said a 29-year-old Tunisian, identified only as Sief Allah H., was taken into custody Wednesday after an investigation uncovered he had procured the materials needed to create ricin in mid-May and even succeeded in creating the toxin earlier this month.
The investigators have not yet established how exactly the suspect planned to use ricin, or how far he had progressed in planning an attack, the GBA said.
The suspect acquired 1,000 castor beans and an electric coffee grinder, as well as other ricin-production-related components from an online store in mid-May, the prosecution said.
"The suspect is believed to have begun procuring material online in mid-May, prosecutors said". Parts of the bean are highly poisonous and can be used to create ricin.
There is now no evidence of a connection with any extremist organization, authorities said.
According to the US Centers for Disease Control and Prevention, the toxin, found naturally in the shell of a variety of bean, works by getting inside cells and preventing them from making proteins they require. A few milligrams are enough to kill an adult if it's eaten, injected or inhaled.
"He had contacts with people in the jihadist spectrum", Schmitt said, using the Arabic word for holy war.
The daily newspaper wrote that he lived in the Chorweiler neighbourhood of Cologne with his wife and four children.
German weekly Der Spiegel reported H. was thought to have followed online IS instructions for building a ricin bomb.
"There is strong suspicion that he had deliberately produced chemical weapons", the Federal Prosecutor's Office (GBA) said in a statement on Thursday.