A court in Germany has sentenced a male nurse to life in prison for killing patients with overdoses of heart medication.

News agency dpa reported that the Oldenburg regional court found the 38-year-old guilty of charges including two counts of murder, and two counts of attempted murder.

Prosecutors had accused the man, identified only as Niels H. in line with German privacy rules, of three murders and two attempted murders during his time working at a clinic in the town of Delmenhorst.

But H. said during the trial that he intentionally brought about cardiac crises in some 90 patients because he enjoyed the feeling of being able to resuscitate them. He said 30 patients died.

He was previously sentenced to 7½ years in prison for attempted murder in 2008.