Psychiatrist and neurologist Hermann Pfannmüller was born in Munich in 1886. After studying medicine and gaining his licence to practice medicine, he was a resident physician in the hospitals and nursing homes of Weilmünster, Ansbach and Kaufbeuren, and, during the First World War, also worked as a hospital doctor. From 1938 to 1945, he headed the Eglfing-Haar mental institution.
Pfannmüller joined the NSDAP for the first time in 1922 and again in 1933 and belonged to the SA. As the head of the department of genetic and racial hygiene at the local health authority in Augsburg, he bore responsibility for the forced sterilizations from 1936 onwards. Since November 1939, he, as a T4 assessor, processed several thousand registration forms of institutional patients, whose murder he recommended in many cases. Patients from Eglfing-Haar were some of the first victims of »Aktion T4« in 1940. Pfannmüller also displayed great zeal when it came to »child euthanasia« and decentralized »euthanasia«. In the »children's ward« of Eglfing-Haar, more than 300 children were killed as of 1940. In two of the »hunger houses« of the institution, he let 440 patients die of starvation or of overdoses of drugs from 1943 onwards.
In 1951, Pfannmüller was convicted and sentenced to five years' imprisonment – reduced to four years on appeal. He died in Munich in 1961.