Welsing was born March 18, 1935, in Chicago. Both her father and grandfather were medical doctors, and her mother was a teacher. She received her bachelor’s degree from Antioch College, and her M.D. from the Howard University College of Medicine. In 1974 Welsing became famous for her paper “The Cress Theory of Color-Confrontation,” which she published while an assistant professor of pediatrics at Howard’s medical school, according to an online bio.

According to Welsing, the work caused such a stir that her tenure at the university was not renewed in 1975. She then spent more than 20 years as a staff physician for the U.S. Department of Human Services in Washington, D.C., and was a specialist in both child and general psychiatry, gaining particular acclaim for her work with young people, notes the bio.

In addition, she was a celebrated scholar who studied the origins of white supremacy from a psychological and biological perspective, and was a proponent of the “melanin theory,” which espouses black superiority due to a higher concentration of melanin in the skin of people of African descent.

As a psychiatrist, Welsing used Freudian symbolism to explain white supremacy, including the interpretation of guns, money, the cross and gold. She faced some controversy regarding her stance on homosexuality, which she said was imposed on black men by whites who wanted to reduce the African population.

Welsing is perhaps best known for her 1991 book, The Isis Papers, which reportedly came about after 20 years of research and analysis from her private practice. It is considered required reading for those interested in the psychological origins and manifestations of white supremacy.

Many prominent Afrocentrists, including Chuck D and Roland Martin, took to social media on Saturday morning to express their grief under the hashtag #FrancesCressWelsing.