A German palliative care doctor has been sentenced to life in prison for killing 15 of his patients.

A Berlin court on Wednesday found the 41-year-old man, identified only as Johannes M. in accordance with German privacy rules, guilty of murdering 12 women and three men between September 2021 and July 2024.

Authorities believe these murders could be just the tip of the iceberg. Prosecutors are currently investigating dozens of other incidents involving the doctor.

His victims were between 25 and 94 years old. The court heard they were all seriously ill but their death was not imminent.

Prosecutors said that during home visits, the doctor administered a lethal combination of several medications without his patients’ consent.

On several occasions they said he set fires to cover his tracks.

In July 2024, shortly before his arrest, prosecutors said the doctor killed two patients in a single day: a 75-year-old man in his home in central Berlin and, a few hours later, a 76-year-old woman in a neighboring district.

They said the doctor tried to set fire to the woman’s house, but failed.

For much of the trial, which lasted about a year, the doctor said nothing. But last month he confessed to having “killed people,” twelve of his seriously ill patients.

He told the court he had convinced himself he was doing the right thing, sparing them “suffering and illness.”

“Throughout it all, I thought this was best for everyone,” he said.

He said he apologized for all the suffering he had caused.

Authorities suspect he has killed more patients. Prosecutors are currently investigating 76 other cases.

German media say that if the new cases are proven and he is found guilty, it would be one of the worst serial murder cases in German history.

The doctor told the court that he would “participate much sooner in the upcoming process.”

At the beginning of the trial, the victims’ relatives told the court they still couldn’t believe it.

The mother of the youngest victim, a 25-year-old woman who died in 2021, was crying. “She never said she didn’t want to live anymore,” he said.

The son of a 72-year-old woman who died in 2024 said his mother had plans to go to the Baltic Sea with his sister. “My mother wanted to continue living,” he said.

The court ordered the doctor’s preventive detention, after serving his prison sentence. He also imposed a lifetime ban on practicing medicine.