The suspect was caught on video sprinkling mysterious substances on co-workers' food during lunch breaks.
A man in Germany has died four years after he ate a poisoned sandwich from his co-worker during a lunch break.
The 26-year-old had been in a coma since he ingested lead acetate and mercury, resulting in severe brain damage.
The death was confirmed by the state court of Bielefeld, which convicted the suspect -- who is identified only as Klaus O. for privacy reasons -- of attempted murder last year and sentenced him to life in prison.
The decision was unusual as long-term jail sentences for attempted murder are rare in Germany.
In 2018, one of Klaus O.'s colleagues at a metal fittings company in a town in northern Germany noticed white powder on his lunch, which prompted his employers to install video surveillance, according to BBC News.
Klaus O. was caught on camera opening lunchboxes and sprinkling mysterious substances on several of his co-workers' food in May of that same year.
The powder contained lead acetate "in amounts that would have been sufficient to cause serious organ damage," police said at the time. A search of the suspect's home found other dangerous substances including mercury, lead and cadmium in a makeshift laboratory.
Two other co-workers suffered serious kidney damage.
Following the trial in March 2019, a judge ruled Klaus O.'s sentence would not be reduced as he is a "danger to the general public."
In court testimony, a psychologist who interviewed Klaus revealed the 57-year-old defendant was experimenting with toxins to see how they affected his colleagues, akin to "a scientist who was testing substances on a guinea pig."