He gained international fame with the crime novel The Glendower Legacy and later with the Vatican thriller The Assassini.
The books posited George Washington as a British spy and the Roman Catholic Church as a criminal organization.
From Dubuque, Iowa, after graduating from college he moved to the Twin Cities, Minnesota, where he and his wife, Kari Sandven, had two children (Thomas Eaton, Rachel Claire).
In 1996, he turned his attention to renovating his childhood home in Dubuque, spending more time in Iowa than New York during his last years.
Diagnosed with terminal cancer in February 2000, Gifford spent his remaining months reading, watching old movies, and chatting with friends and family.