The 32-year-old suspect was immediately placed in psychiatric care and may not be criminally culpable due to her mental state, police and prosecutors in the western city of Darmstadt, near Frankfurt, said in a joint statement.
Investigators probing the case from last August at the city’s Technical University (TU Darmstadt) said that attention turned to the woman based on forensic traces left at the scene of the crime and accounts from more than 1,000 witnesses.
“The findings indicate that the suspect felt persecuted by the affected staff,” they said.
Police had raced to the campus when seven people in one building reported “serious health problems including symptoms of poisoning” after consuming food or drink to which a “harmful substance” had been introduced.
Two of the victims had to be taken to a hospital in nearby Frankfurt while others were treated at the scene.
A 30-year-old was briefly in a critical condition and his skin reportedly turned blue in what police said was an effect of the toxin.
Milk and water containers were among the items apparently spiked the weekend before with a chemical, which police described as having a noticeably “pungent smell”.
The affected building, part of the Department of Materials- and Geosciences, was cordoned off and foodstuffs on site taken away for investigation in what the university described as a “poison attack”.
Several poisoning incidents in Germany have made headlines in recent years.
In December 2019, five newborn babies were poisoned with morphine, but a nurse who was initially arrested for the crime was subsequently released.
The babies, aged between one day and five weeks at the time, all survived the attempted poisoning. No one has been charged over the case.
A German court in 2019 sentenced Klaus O. to life in prison for spiking his colleagues’ sandwiches with a poisonous powder containing lead, mercury and cadmium compounds.
He was caught red-handed in 2018 trying to poison other colleagues.