A German court has sentenced a 42-year-old nurse to life in prison for killing no fewer than 85 patients in his care.

The nurse, identified as Niels Hoegel, is believed to be the most prolific serial killer in the country’s post-war history was handed a life sentence on Thursday.

Judge Sebastian Buehrmann called Hoegel’s killing spree “incomprehensible”.

He was said to have murdered patients selected at random with lethal injections between 2000 and 2005 until he was caught in the act.

According to DW, Hoegel was originally accused of having murdered 100 patients while on duty as a nurse from June 1999 until 2005. The victims, people of all ages and backgrounds, some in bad health and others on the mend, had trusted the medical centers in Lower Saxony where Högel worked with their lives.

The court in Oldenburg handed down Germany’s most severe form of a life sentence which precludes the chance of an early release after serving 15 years. A prisoner sentenced to life imprisonment can usually apply for parole after 15 years, but if the court judges there is a “severe gravity of guilt,” as it did in Hoegel’s case, parole can be delayed for a non-specified period beyond that time.

While working at a clinic in Oldenburg, Northwest Germany and a hospital in Delmenhorst, Hoegel deliberately induced cardiac arrest in patients by injecting them with certain drugs. He then resuscitated them to win everyone’s admiration. But many of Högel’s stunts went awry, and patients died.

A former colleague told the mass-circulation German newspaper Bild that Högel “always pushed everyone else aside” when resuscitating patients. The man, also a former nurse, said less-experienced doctors even expressed their appreciation that Hoegel was around. The killer’s unsuspecting colleagues nicknamed him “resuscitation Rambo.”

During closing arguments at the district court in Oldenburg on Wednesday, Högel addressed friends and relatives of his victims.

“I would like to sincerely apologize to every single individual for all that I have subjected them to over the years,” the 42-year-old Högel told the court.