A nurse already serving a life sentence for two murders may have killed more than 100 of his patients out of "boredom".
Niels Hoegel was convicted in 2015 of two murders and two attempted murders at a German hospital and was sentenced to life in prison, reports The Independent.
The investigation into the 40-year-old nurse was widened when Hoegel admitted killing up to 30 people during his trial. Hoegel said he intentionally administered fatal doses of heart medication to patients because he was bored and enjoyed resuscitating them, often to impress his colleagues. He was frequently unsuccessful in his attempts at resuscitation and many of his patients died.
In August 2017 investigators announced they had determined Hoegel may have killed at least another 84 people, in addition to the murders for which he had already been convicted. At the time they said they were waiting on the toxicology results of a further 41 deaths, which have now been concluded. As part of their investigation, police exhumed 134 bodies from 67 different cemeteries.
Hoegel first aroused suspicions when records noted the rates of death and resuscitations rose during his shifts at a clinic in Oldenburg, where he worked from 1999 to 2002. He went on to work at a hospital in Delmenhorst from 2003 and 2005, where once again an unusual number of patients died while Hoegel was working, according to the BBC.
The killer was eventually caught when a previously stable patient developed an irregular heartbeat after being resuscitated while Hoegel was in his hospital room.
During his trial in 2015 Hoegel apologised for the murders and said the decisions to commit his crimes were "relatively spontaneous". He claimed each time one of his victims died, he swore he would never do it again, but his resolve would then fade over time.
If Hoegel was found guilty of all the deaths, he would become one of Germany's worst post-war serial killers.