BERLIN (AP) — Federal prosecutors say they have filed charges against a 30-year-old Tunisian and his 43-year-old German wife who are accused of producing biological weapons for an attack in Germany.

Prosecutors said Thursday that Sief Allah H. and Yasmin H., whose full names were withheld in line with local privacy rules, were followers of the ideology of the Islamic State extremist group. They bought thousands of castor beans and developed the toxin ricin to carry out an attack on a crowded public place in Germany. They also turned fireworks into explosives.

H. also tried twice unsuccessfully to travel to Syria in 2017 to join the IS group. He and his wife were arrested in 2018 in their Cologne apartment, where investigators found castor bean seeds and ricin along with bomb-making components.