The authorities in Germany charged a Berlin palliative care doctor on Wednesday with the murder of 15 patients over the course of three years. The public prosecutor also said that a further 75 patient deaths were being investigated as suspicious.

If convicted in the 15 deaths, the doctor would be the most prolific serial killer in Europe since a German nurse killed at least 85 patients two decades ago.

The doctor charged on Wednesday, a 40-year-old man whose name was not released, in keeping with Germany’s strict privacy laws, is accused of having killed the patients from 2021 to 2024 by giving them a powerful narcotic and then a muscle relaxant — essentially sedating them before stopping their breathing. He has not admitted to the charges, prosecutors said.

In some cases, he is accused of setting fire to the patients’ apartments to hide the evidence. In at least one instance, he is accused of calling an ambulance to mislead investigators.

Under German law, the maximum sentence for murder is life in prison with the possibility of parole after 15 years. But the crimes in this case are so unusual that the public prosecutor has requested a special security custody, meaning that if the doctor were convicted, he would be kept in prison after the conclusion of the sentence for the safety of the wider population.

The doctor is being held at Moabit Prison in Berlin. He has been in jail since August, when the district attorney ordered his arrest on suspicion that he had killed four of his patients. Since then, a team of investigators has found more patients they suspect to have been victims.