A man is feared to have killed up to 21 of his co-workers over the last 18 years by sprinkling poison on their lunches.
The suspect was arrested after police say he was caught on CCTV putting something onto a colleague’s meal.
Police said they had arrested a 56-year-old man suspected of attempting to kill a colleague at a company in the town of Schloss Holte-Stukenbrock in Germany.
Detectives have not named him, any of his alleged victims, or the company where they all worked.
But local media have named the firm as a ARI-Armaturen – which has a factory in the town.
Tilo Blechinger, a manager for the metal fittings manufacturer, told the DPA news agency: “In the beginning we thought it was a misconceived prank between co-workers, and not a murder attempt.”
He also revealed that the suspect had worked for the company for 38 years.
The latest potential victim had noticed something suspicious in his lunch and notified his bosses and the authorities, police said.
And according to the Germany’s public broadcaster WDR, two other employees are in a coma and another man is on dialysis.
Video footage revealed the suspect spreading a white powdery substance on the victim’s food.
Tests showed it was a poison that could have caused severe organ damage.
During a search of the suspect’s apartment, police found toxic chemicals such as mercury, lead, and cadmium, they said.
Further investigation uncovered 21 cases, dating back to 2000, of employees at the same company who had died of heart attacks or cancer shortly before retiring.
Experts concluded that heavy metal poisoning could have been the cause of the illnesses that led to those deaths.
The suspect’s motive was not clear because he remained silent about the allegations, the police said.
A 15-member murder squad has been brought together to investigate the deaths and interview relatives of the victims and the doctors who treated them.
The officials are also considering exhuming the bodies to determine the presence of metal.