BERLIN — A homemade batch of the deadly toxin ricin was found in a Tunisian national's apartment in Germany, prosecutors said Thursday.

A written statement said a 29-year-old — identified only as Sief Allah H. — was arrested on Tuesday night on suspicion on violating the country's War Weapons Control Act.

He is accused of having started procuring material, including a large quantity of seeds needed for the creation of ricin, online in mid-May.

The suspect succeeded in creating the toxin this month and investigators found it during a search of his Cologne apartment, the statement said.

The authorities are still investigating exactly how the suspect planned to use the ricin, but stated he was working on a “biological weapon” and there was "initial suspicion" that he could have been preparing a terrorist attack.

Prosecutors said they currently have no evidence of a connection with any extremist organization.

Elmar Thevessen, a terrorism expert with NBC News' German partner ZDF, said: "Ricin is deadlier than then the venom of a cobra. A tiny amount is enough to kill an adult. In can be dissolved in water or added to food. There is no antidote."