Question: David Edgar wrote a play based on a book by Gitta Sereny, who was a biographer with what nationality?
Sentence (from "Gitta Sereny"): Gitta Sereny, CBE (13 March 192114 June 2012) was an Austrian-British biographer, historian, and investigative journalist who came to be known for her interviews and profiles of controversial figures, including Mary Bell, who was convicted in 1968 of killing two children when she herself was a child, and Franz Stangl, the commandant of the Treblinka extermination camp.
Relevant evidence: Yes