Barbara Neely, the pioneering mystery novelist known for her novels featuring detective Blanche White, has died of a heart-related illness at 78, the Washington Post  reports.

Her death was confirmed by her sister, Vanessa Neely-Peterson, and her publisher, Brash Books.

Neely was the author of four novels featuring Blanche White, a cleaning person with a talent for solving crimes. The books were considered the first American series of novels featuring an African American woman, the Los Angeles Times reports.

The first book in the series, Blanche on the Lam, was published in 1992 to considerable critical acclaim. Three more would follow: Blanche Among the Talented Tenth, Blanche Cleans Up, and Blanche Passes Go.

Her novels were known for addressing themes such as racism, class, and misogyny. A reviewer for Kirkus called the last novel in the series “a trenchantly written feminist manifesto for women of color, women who’ve survived abuse, and men who don’t mind having their hackles raised.”

Neely came relatively late to writing, publishing her first book in her early 50s. Before she was an author, she worked as an activist and a radio show host.

The Mystery Writers of America said in a statement, “She was an inspiration, a trailblazer, and a remarkable talent and voice whose loss is deeply felt. Her talent and memory will live on forever in her wonderful books.”

The group celebrated Neely last December, giving her the Grand Master Award. The organization praised her for addressing “themes and issues that extend beyond mystery and into political and social commentary.”

Michael Schaub is a Texas-based journalist and regular contributor to NPR.