Adam Zagorin, who has turned his superior investigative instinct onto subjects ranging from Jack Abramoff to Guantanamo Bay in recent years, delivers a must-read piece in this week’s print magazine on newly discovered irregularities in the investigation that put former Alabama Governor Don Siegelman in prison. Zagorin has as exclusive based on confidential FBI and state investigative records involving one of the principle prosecution witnesses used to indict Siegelman. In interviews with investigators, the witness claimed he made illegal campaign donations not just to Siegelman but also to prominent Alabama Republicans, including now U.S. Senator Jeff Sessions — but investigators never pursued those claims. Instead, they focused only on what the witness alleged about Siegelman. The Siegelman case has already become a flashpoint in the debate about the politicization of the Bush Justice Department. Zagorin’s story shows why.