Walker graduated from Duke University in English and took up high school teaching. She married in 1967 to Lee Walker who became president of Dell Computers, living in New York and Virginia before moving to Austin, Texas. They have two daughters, Amanda and Susannah but are now divorced. She continues to live in Austin.
She began writing in her mid-forties, which she characterized as " 'pretty late to start' ". She spent two years writing her first published thriller, Zero at the Bone, which was published in 1991. Her second Texas-based mystery, Red Scream, was Walker's first to feature sleuth Molly Cates.Red Scream won the Best Mystery Edgar Award in 1993.Under the Beetle's Cellar, published in 1995, was Walker's third mystery.