A former nurse who liked to put patients into cardiac arrest because he enjoyed the feeling of being able to resuscitate them has been convicted of 85 counts of murder in a court in northwestern Germany.

The Oldenburg court on Thursday sentenced 42-year-old Niels Hoegel to life in prison and noted the “particular seriousness of the crimes” to ensure he serves beyond the standard 15-year term, the dpa news agency reported.

The killings took place while Hoegel worked at a nurse at two hospitals in northwestern Germany from 2000 to 2005.

In all Hoegel was charged with 100 counts of murder and it was not immediately clear why the court only found him guilty on 85 counts.

Hoegel apologized in a closing statement at the end of the seven-month trial.