Emmett "Curly" Thornton died in Montana at age 50, on 21 January 1999. But the cause of death is not easily found: internet rumors say he was murdered, which would not be surprising given that he was accused of child abuse, rape, and domestic violence. But the only newspapers that have this information do not seem to be available online. You may want to contact the Billings, Montana or Butte, Montana public library, and see if they can check his obituary for you.
suicide
Ernie Thornton died in 1969.
Curly Ray Cline died in 1997.
Willard Thorp died in 1992.
Jimmy Don Thornton died on October 3, 1988, in San Francisco, California, USA of heart failure.
suicide
Nigel Thornton died in 1982.
A.G. Thornton died in 1969.
Charley Thornton died in 2004.
Abraham Thornton died in 1860.
Barbara Thornton died in 1998.
Peter Thornton died in 2007.
Arthur Thornton died in 1915.
Thornton Stringfellow died in 1869.
Isaac Thornton died in 1669.
Thornton Burgess died in 1965.
Hugh Thornton died in 1962.