The 32-year-old suspect was believed to have procured lethal poisons including cyanide and ricin, but authorities have confirmed that no evidence was found in his flat.
ADVERTISEMENTAnti-terror investigators in Germany have arrested an Iranian national on suspicion of preparing a religiously motivated attack.
Emergency service personnel wearing protective suits and oxygen masks searched a flat in Castrop-Rauxel, in the Ruhr region, for biological weapons.
The 32-year-old suspect was believed to have procured lethal poisons including cyanide and ricin, but authorities have confirmed that no evidence was found on the premises.
A total of two men were reportedly taken into custody.
The highly toxic ricin is listed as a biological weapon, while even the smallest amount of cyanide can have a lethal effect on humans.
Investigations are ongoing to establish how far attack plans had progressed and whether there was a concrete target.
Click on the video in the player above to find out more.