The 26-year-old collapsed in late summer 2016 after returning from work at a valve factory in western town Schloss Holte-Stukenbrock, south of Bielefeld, where he had eaten sandwiches sprinkled with a poisonous powder containing lead, mercury and cadmium compounds by colleague Klaus O.
He suffered irreparable brain damage from the substances.
Following the victim's death, “the court decided today at prosecutors' request that the deceased's body must be autopsied” in case of a new legal proceeding, Bielefeld state court spokesman Guiskard Eisenberg told AFP.
In March last year, the court sentenced the then-57-year-old perpetrator Klaus O. to life in prison for attempted murder.
He was caught red-handed in 2018 trying to poison other colleagues.
Workers at the factory suffered grave kidney damage, prompting judges to sentence Klaus O. also for serious and dangerous bodily harm.
A psychologist told the court that “in his statements about his motive, he seemed like a scientist testing substances out on a rabbit,” German media reported at the time of the trial.
The perpetrator has appealed his conviction to Germany's top court.
The federal court could now throw out or allow his appeal, or overturn the original conviction – allowing a potential new conviction for murder or another form of homicide following the victim's death, spokesman Eisenberg said.
Nevertheless, given the severity of the original sentence and a general ban on a higher sentence resulting from an appeal, there is no chance of a harsher punishment for the poisoner, he added.