The cause was cancer, his daughter, Misti Bragg, told The Associated Press.
The Prisonaires quintet became standard-bearers for Gov. Frank Clement's controversial prison-reform program, which emphasized rehabilitation. In the summer of 1953, under heavy guard, the singers traveled from their Nashville prison to Memphis to record at Mr. Phillips's fledgling Sun Records. The session yielded the mournful hit "Just Walkin' in the Rain," of which Mr. Bragg was the co-writer, and a feature story in a local newspaper.
"It was the song that put Sun Records on the map, and very likely the item that captured the attention of Elvis Presley as he read about the studio, the label, and painstaking Sam Phillips," the biographer Peter Guralnick wrote in "Last Train to Memphis: The Rise of Elvis Presley."
That same summer, Presley made his first demonstration recordings at Sun. In 1961 he visited Mr. Bragg in prison.
"The Prisonaires were pioneers in that they were among the first R & B vocal groups to record and have hit records released in the South," Michael Gray of the Country Music Hall of Fame and Museum said on Thursday.
Mr. Bragg, born John Henry Bragg, was convicted of rape in 1943. He always denied the charges, and Governor Clement commuted his sentence in 1959. He soon returned to prison on a parole violation and spent time in and out of incarceration until 1977.
Besides his daughter, Mr. Bragg's survivors include two grandchildren. His wife, Gail Green Bragg, died in 1977