Herbert Stempel, a contestant on NBC’s Twenty-One who helped uncover the quiz show rigging scandals of the 1950s, has died at the age of 93.

His death, which had not been publicly announced, was confirmed by a former stepdaughter, Bobra Fyne, according to the New York Times.

Mr Stempel was portrayed by John Turturro in the 1994 drama Quiz Show, which was directed by Robert Redford.

Mr Stempel was born in the Bronx on December 19, 1926, the son of Solomon and Mary Stempel. He was a gifted student with a prodigious memory.

As a child, he represented PS 6 on the radio show Americana Quiz, and remained undefeated for weeks. He attended Bronx High School of Science and scored at genius level on an IQ test.

Mr Stempel worked for the post office, served in the US Army from 1946 to 1952 and enrolled at City College under the GI Bill.

He was also a fan of quiz shows such as The $64,000 Question, Tic Tac Dough and Twenty-One. He wrote to Twenty-One, took a test and was invited on the show in 1956.

Mr Stempel was coached on the answers and given directors for how to deliver them and won about $US50,000 ($75,000) in five weekly appearances on Twenty-One.

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Producer Dan Enright then selected Charles Van Doren, a dapper English instructor at Columbia University, to replace Mr Stempel on the show.

Mr Stempel lost by deliberately giving the wrong answer to the question of which movie had won the Academy Award in 1955, saying it was On the Waterfront instead of Marty.

A promise by Mr Enright to find Mr Stempel another panel show slot went unfulfilled.

“He just completely forgot I ever existed,” Mr Stempel later told the Archive of American Television, according to the Associated Press.

“He had a picture of Charles Van Doren in his office when I walked in there and all he could do was praise Charles Van Doren, tell me what a great contestant is.”

Mr Stempel then called several journalists to assert that Twenty-One was rigged while Mr Enright insisted that Mr Stempel was bitter about losing.

Herbert Stempel (left), with reporter Joseph Breu, he arrives at a district attorney’s office during the quiz show investigation. Photo: Getty

The scandal broke open in 1958 when Albert Freedman, a Twenty-One producer who had coached Mr Van Doren, was indicted for perjury. Mr Van Doren subsequently pleaded guilty to second-degree perjury.

After the scandal, Mr Stempel became a high school social studies teacher in New York and later worked for the New York City Department of Transportation.

He assisted in a 1992 documentary about the scandal for the PBS series American Experience and was a paid consultant on Quiz Show, which also starred Ralph Fiennes as Van Doren.

Mr Stempel made a cameo appearance in Quiz Show, portraying a different contestant being interviewed by a congressional investigator, portrayed by Rob Morrow.

-AAP