In early 2006, Carr became a book author with the publication of the "New York Times"-rated best-seller "The Brothers Bulger", about brothers Billy and Whitey Bulger. Whitey was the third boss of the Winter Hill Gang. Carr's second book, "", was released in April 2011, two months before Whitey Bulger (then under the name Charlie Gasko) was arrested after sixteen years on the run. About Johnny Martorano, "Hitman" was also rated a best-seller by "The New York Times". In 2013, "Rifleman: The Untold Story of Stevie Flemmi" was published. It was followed a year later by "Ratman: The Trial and Conviction of Whitey Bulger".