Image copyright AFP/ Getty Image caption The nurse, known as Niels H, was jailed for life two years ago 
 
 A nurse serving a life sentence for murdering two patients in northern Germany is now a suspect in at least 84 other murder cases, police say. 
 
 The 40-year-old, named only as Niels H under German reporting rules, was convicted of attempted murder in 2006 and murder in 2015. 
 
 His victims received lethal drug doses at units where he worked. 
 
 Relatives of patients who died in clinics where he worked had urged police to investigate further. 
 
 A commission was set up in 2014 to investigate the scale of his crimes, which could make him Germany's worst post-war killer. 
 
 The medication caused heart failure or the collapse of patients' circulatory systems. 
 
 Judges said he was motivated by a desire to win approval by resuscitating the patients he had drugged. 
 
 During his 2015 trial, he admitted applying the drug to about 90 people at an intensive care clinic in the town of Delmenhorst. 
 
 Media playback is unsupported on your device Media caption Niels H hid behind a folder during his trial 
 
 Police say the abnormalities stretch back to 2000 at another clinic in Oldenburg. 
 
 They said staff had a meeting there in 2001 to discuss the strange levels of deaths and resuscitations, but did not report the levels to police, and Niels H was able to move to the Delmenhorst clinic. 
 
 A special police commission was set up in 2014 to investigate the case. 
 
 It has been analysing hundreds of medical records and exhumed 134 bodies to test samples for drug residue. 
 
 The investigations have been made more difficult because many patients had been cremated. 
 
 "The findings continue to breach any imagination," said Oldenburg police chief Johann Kuhme. "It is simply not possible to say how many people were killed." 
 
 Mr Kuhme warned the number could still rise further. The new charges are now likely to be filed at the beginning of 2018, he said. ||||| A former nurse has admitted to killing 100 patients in his care, on the first day of his trial in the biggest serial killing case in Germany’s post-war history. 
 
 Niels Hoegel, 41, has already spent nearly a decade in prison on a life term for other patient deaths. He is accused of intentionally administering medical overdoses to victims so he could bring them back to life at the last moment. 
 
 As the proceedings opened in the northern city of Oldenburg, the presiding judge, Sebastian Buehrmann, asked whether the charges against him were accurate. Hoegel replied “yes”. 
 
 “What I have admitted took place,” he told the courtroom crowded with dozens of grieving relatives. 
 
 As the proceedings began Buehrmann said the main aim of the trial was to establish the full scope of the murder spree that was allowed to go unchecked for years at two German hospitals. 
 
 “We will do our utmost to learn the truth,” he said. “It is like a house with dark rooms – we want to bring light into the darkness.” 
 
 After a minute of silence for the victims, the bearded, heavyset Hoegel listened impassively, his head lowered, as public prosecutor Daniela Schiereck-Bohlmann read out the name of each dead patient and the charges against the defendant. 
 
 Prosecutors say at least 36 were killed at a hospital in Oldenburg where he worked, and about 64 more at a clinic in nearby Delmenhorst, between 2000 and 2005. 
 
 More than 130 bodies of patients who died on Hoegel’s watch have been exhumed. Investigators have said the case is “unprecedented in Germany to our knowledge”. 
 
 One of the more than 100 co-plaintiffs in the trial, Christian Marbach, said it was a scandal that Hoegel had been allowed to kill with impunity for so long without hospital authorities or law enforcement intervening. 
 
 “They had everything they needed [to stop him] – you don’t have to be Sherlock Holmes,” said Marbach, the grandson of one of the patients. 
 
 He later expressed surprise about Hoegel’s quick confession. 
 
 “I didn’t expect it to happen today,” he said. “We now have a chance to make some real progress.” 
 
 Hoegel was caught in 2005 while injecting a patient in Delmenhorst with an unprescribed medication. He was sentenced in 2008 to seven years in prison for attempted murder. 
 
 A second trial followed in 2014-15 under pressure from families of his alleged victims, who accused prosecutors of dragging their feet. 
 
 He was found guilty of murder and attempted murder of five other victims and given the maximum sentence of 15 years. 
 
 It was then that Hoegel confessed to his psychiatrist of at least 30 more murders that he committed in Delmenhorst. That prompted investigators to take a closer look at suspicious deaths in Oldenburg. 
 
 Investigators say the final toll could be more than 200 but fear they might never know for sure because the bodies of many potential victims were cremated. 
 
 Hoegel appears to have followed a similar procedure each time, first injecting a medication that triggered cardiac arrest, followed by an often futile attempt at resuscitation. 
 
 Prosecutors say he was motivated by vanity, to show off his skills at saving lives, and by simple “boredom”. 
 
 The choice of victim appears to have been entirely random, with their ages ranging from 34 to 96. 
 
 Killing in itself was never his aim, according to one psychologist who evaluated him. When he managed to revive a patient, he was sated, but only for a few days, the expert said, adding: “For him, it was like a drug.”
– He has been convicted of killing two and attempting to murder two more—and he could actually be "Germany's worst post-war killer," reports the BBC. Niels Hoegel, 40, was sentenced to life in prison in 2015 for those crimes, but prosecutors voiced their belief that the nurse had killed many more while working at clinics in Oldenburg (from 1999 to 2002) and Delmenhorst (from 2003 to 2005), reports the AP. Now police are giving a sense of just how many more: at least 84. Hoegel said at trial that he wanted to play the hero and drugged his patients so that he could then resuscitate them and win praise. Except a commission established three years ago to determine the breadth of his crimes has found that many patients ended up receiving lethal doses of drugs that brought on heart failure or destroyed the circulatory system. The BBC reports that 134 bodies have been exhumed and tested for traces of the drug, but "it is simply not possible to say how many people were killed," per Oldenburg police chief Johann Kuhme. That's in part because many of his patients were cremated. The AFP quotes chief police investigator Arne Schmidt as describing the death toll as "unique in the history of the German republic." There is "evidence for at least 90 murders," he said at a press conference, "and at least as many [suspected] cases again that can no longer be proven." Kuhme faulted the clinics for having "hesitated to alert authorities," saying the death toll could have been much lower if they had. New charges against Hoegel will likely be filed next year. (This nurse says she would get a "red surge" before killing one of her patients.)