Federal prosecutors in Germany have accused a Tunisian man of creating a biological weapon for use in an Islamic attack.

The suspect, 29-year-old Sief Allah H., was arrested Tuesday in Cologne following a raid on his apartment.

German authorities said Thursday that Sief used castor bean seeds to create the deadly toxin ricin, but are still investigating how he planned to use it.

“We don’t know how, or how widely, the ricin was to have been distributed,” said Markus Schmitt, the prosecutors’ spokesman.

Sief began ordering materials online to develop the toxin in May before successfully producing ricin this month, the prosecutors said, declining to reveal the amount taken during the raid.

Schmitt added that while Sief is not believed to have belonged to any terrorist group, the suspect was known to have communicated in one way or another with extremists.

“He had contacts with people in the jihadist spectrum,” Schmitt said.

According to the Associated Press, German newspaper Bild reports that U.S. intelligence alerted Germany to Sief after detecting his online purchases.

Bild also reported that the suspect, who allegedly lived with a wife, a convert to Islam, and four children, intended to make a ricin bomb after locating instructions posted online by the Islamic State.

Schmitt declined to confirm or deny Bild’s reporting when asked by the AP.

“The seeds of the castor bean plant are naturally poisonous and can be used to create ricin. The substance kills the body’s cells by preventing them from creating protein,” the AP notes. “A few milligrams are enough to kill an adult if it’s eaten, injected or inhaled. Early symptoms include chest pain, breathing difficulties and coughing.”