A new biography, American Scoundrel by Kai Bird and Susan Goldmark, examines the life of Roy Cohn, the New York mob lawyer who mentored Donald Trump in the 1970s and 80s and is credited with shaping much of his combative approach to business, politics and the law. The book, subtitled "Dark Journey from Joe McCarthy to Donald Trump", traces Cohn's path from prosecuting Julius and Ethel Rosenberg to becoming a fixer for organised crime figures and, later, a formative influence on the future president, who once famously asked "Where's my Roy Cohn?" during the Russia investigation scandal.

Bird, a Pulitzer prize-winning biographer previously known for American Prometheus, the basis for Christopher Nolan's Oppenheimer film, spoke to Trump four times by phone while researching the book, describing conversations in which Trump reshaped his own account of first meeting Cohn at Le Club in Manhattan in 1973. Bird noted that most conservative media figures, including Fox News hosts and Steve Bannon, declined to engage with the book, while Joe Rogan reviewed the galleys but said he was not interested. The biography, published on Tuesday, is described as fair but unflinching in its portrayal of Cohn's ruthless tactics, which Bird argues Trump absorbed and continues to apply.