At a daughter's urging, she entered a mystery-writing contest sponsored by St. Martin's Press.
In nine months, she was told that her first novel, The Doctor Digs a Grave, had won the Malice Domestic Award for best traditional mystery. St. Martin's agreed to publish it in 1998 and sent her a $10,000 advance.
A year later the book won an Agatha - the mystery writers' equivalent of an Oscar - from Malice Domestic.
A review in Mystery Scene magazine said of The Doctor Digs a Grave: "The plot is as mysterious as old-fashioned mysteries but the telling is sleek and fashionable and right up to date."
The protagonist of her first series of books was Dr. Andrew Fenimore, modeled after her cardiologist husband.
Her novels never climbed the best-seller lists, but they sold steadily and are in libraries all over the world.
Robin Hathaway was born in Germantown on Feb. 12, 1934, the daughter of John Wallace Hathaway and Elizabeth Foster McCloy.
She was a graduate of Germantown Friends School. In 1956, she received a bachelor's degree in English from Smith College. She married in 1961.
Mrs. Keisman worked as a volunteer tour guide at Stenton, a historic home in Germantown. She and her husband lived in New York in addition to Brewerytown.
She wrote eight mysteries. The others are: The Doctor Makes a Dollhouse Call (2000); The Doctor and the Dead Man's Chest (2001); The Doctor Dines in Prague (2003); Scarecrow: A Mystery (2003); Satan's Pony: A Mystery (2004); The Doctor Rocks the Boat (2006); and Sleight of Hand: A Jo Banks Mystery (2008).
She was a member of the Mystery Writers of America and Sisters in Crime.
Elena Santangelo, a friend and writer, said Mrs. Keisman "was incredibly curious. She was interested in people. She would just observe things about people around her that wouldn't have even occurred to me, and she would build that into her books."
Mrs. Keisman's daughter Anne Keisman Cissel said, "She was really inspiring because she never gave up when she was trying to get her books published."
In addition to her husband and daughter, Mrs. Keisman is survived by another daughter, Julie Keisman Miller; three grandchildren; and a brother.
Services were being planned.
Contact Vernon Clark at 215-854-5717 or firstname.lastname@example.org.