40-year-old suspect Niels Högel is already serving a lifetime prison sentence for two further counts of murder and now, the local law enforcement is investigating his involvement in the deaths of dozens of additional patients.
"The murders could have been prevented", said Kuehme, with investigators believing that those responsible at the time could have acted faster. "As if that were not enough, we have to accept realize that the real scale of the killings is probably many times worse".
The resulting evidence suggests that he may have killed at least 84 more people, officials said.
Niels Hoegel, 40, was jailed in February 2015 for two murders of intensive-care patients at the Delmenhorst hospital near the northern city of Bremen.
Authorities have subsequently investigated hundreds of deaths, which included exhuming bodies of former patients in the clinics where Hoegel worked in Delmenhorst and Oldenburg in northwest Germany.More news: Thousands stuck on cruise ships after Hurricane Harvey
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Hoegel's activity came to light in 2005 when a colleague witnessed him injecting a patient.
Authorities are already pursuing criminal cases against former staff at the two facilities. He previously worked at Oldenburg hospital from 1999 to 2002, and confessed to investigators that he also killed patients at that location. During the trial, Hoegel reportedly admitted that he had triggered cardiac arrests in about 90 of his patients. All to impress co-workers with his resuscitation skills.
His confession led the police to launch Kardio- a special forensic investigation to determine the cause of death of the patients.
Prosecutors are expected to try Hoegel on some of the killings but because Germany's judicial system does not allow for consecutive sentences, future convictions will not affect his life term.
The identities of the suspected 84 victims haven't been released.