He was meant to keep patients alive but it seems Niels Hoegel, 40, was doing the opposite of that.
In 2015, Hoegel was sent to jail for two murders and the attempted murders of several intensive care patients at Delmenhorst hospital in Bremen, Germany.
After exhuming and examining more bodies, police said on Monday, August 28, 2017, that more evidence of murders has been discovered.
"The death toll is unique in the history of the German republic," said Arne Schmidt, the chief police investigator. "[There was] evidence for at least 90 murders, and at least as many [suspected] cases again that can no longer be proven," he said at a press conference.
Niels Hoegel has admitted to causing heart failure in his patients by injecting them. His plan was to revive them and be a hero among his pairs. Whenever he succeeded he felt happy and when he failed he became sad.
His confession led the police to launch Kardio- a special forensic investigation to determine the cause of death of the patients. 130 bodies were exhumed and tested for the deadly drug.
In 2015, Hogel was sentenced to life for his earlier crime.