Waugh's son, Lawrence, confirmed his death Saturday, saying it occurred Dec. 8 in a nursing facility in Torrington, Conn., after a brief illness.
He had moved there recently to be near one of his daughters after living for decades in Guilford, Conn., where he was a former first selectman.
Waugh's dozens of novels -- numbering almost 50, including some he wrote under pen names -- earned him a Grand Master Award in 1989 from the Mystery Writers of America.
The honor puts him in the company of Stephen King, Mary Higgins Clark, Mickey Spillane, Alfred Hitchcock and Agatha Christie.
Hillary Baldwin Waugh was born June 22, 1920, in New Haven, Conn. He graduated from Yale University in 1942 and served as a Naval Air Corps aviator in World War II.
Waugh has said he started his first mystery novel while stationed in Panama to fight the boredom of his off-duty hours.
His first novel, "Madame Will Not Dine Tonight," was published in 1947 and became the first in a long string of mysteries in which the characters used real police techniques to solve mysteries.
That was a clear departure from the genre in which a sole private detective, squirreling away facts and relying on his or her wits and instinct, emerged with all the answers.
"I was tired of reading about these super-detectives and a police force composed of a bunch of bumbling idiots," Waugh told the New York Times in 1990.
"I wanted to get away from the neat little corpses with the perfect bullet through the head, and instead write a story as it really happened."
One of his early novels, the 1952 story "Last Seen Wearing," is listed by the Mystery Writers of America as one of the top 100 mystery novels of all time.
Waugh's interests were not limited to literary pursuits. In 1971, he was elected to a two-year term on the Republican ticket as first selectman of Guilford, where he lived for decades.
He used Connecticut as a setting for many novels, changing town names slightly but enjoying the juxtaposition of bucolic small-town life against the commotion and suspicion caused by crimes in tight-knit communities.
In addition to his fictional work, Waugh wrote a 1990 book, "Hillary Waugh's Guide to Mysteries and Mystery Writing." He also was a small-town newspaper editor for a year in nearby Branford, Conn., and was a longtime board member and officer of the Mystery Writers of America.
Waugh had three children -- Lawrence, Sandra and Kathryn -- with his first wife, the former Diana Taylor, from whom he was divorced in 1980. He was married to fellow mystery writer Shannon OCork from 1983 to 1995.
Until declining health sent him to a nursing home, Waugh lived in the same Guilford cottage where he had spent his boyhood summers and did much of his writing. The family plans a private memorial service there next summer.