Former nurse Niels Hoegel, accused of multiple murder and attempted murder of patients, covers his face with a file at the district court in Oldenburg, Germany, Feb. 26, 2015. Credit: Carmen Jaspersen | dpa via AP

BERLIN — Niels Hoegel, a 41-year old former German nurse, confessed Tuesday to one of Europe’s most gruesome mass murder cases since World War II and admitted to killing 100 patients between 2000 and 2005.

Hoegel had already been sentenced to life in prison after being charged with at least six murders and several more attempts. But prosecutors pushed for a new trial after details indicated that Hoegel may have killed 100 more victims, injecting them with deadly drugs such as lidocaine and calcium chloride, according to prosecutors who said Hoegel acted out of “boredom.”

The death toll may be even higher than currently assumed, because some victims — ages between 34 and 96 — were cremated. More than 130 other bodies were exhumed during the investigation.

As his trial got underway Tuesday, Hoegel admitted that the accusations were largely correct. “That’s the way it is,” he said.

His mass murder went unnoticed for years, partially because many of the patients he treated were already critically ill and because Hoegel tried to resuscitate his victims after deliberately putting them on the brink of death. In some cases, patients survived the ordeal, but records show that fatality rates regularly increased when Hoegel was on shift.

Investigators are also probing the responsibility of the hospitals where Hoegel worked. Authorities said that staff there was aware of irregularities, but failed to act. Even when Hoegel was caught administering his deadly drug cocktail to one victim in 2005, hospital officials did not immediately intervene. They only reached out to authorities after Hoegel killed yet another patient, using the same method.

The nurse has claimed that he acted spontaneously and repeatedly vowed to never kill again. In 2015, he apologized for his crimes, saying that he was “honestly sorry.”

Hundreds of relatives backed the new trial against Hoegel, even though the former nurse’s sentence won’t substantially change. German criminals sentenced to life in prison usually only spend 15 years behind bars. German laws also does not allow for consecutive prison terms, so Hoegel could theoretically walk free within little more than a decade, unless he is barred from an early release at the end of the trial that is now underway.

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