Crown Publishers will release Kitty Kelley’s unauthorized biography of Oprah Winfrey April 13 with a first printing “in excess of a half-million copies,” the publisher announced late Thursday afternoon. Oprah: A Biography will be released in the U.S. and Canada simultaneously in hardcover, audio, and electronic formats.

Kelley, who has written a string of bestselling biographies of the rich and famous, conducted 850 interviews for the Oprah book during three years of research. According to Crown, she finished the manuscript earlier this month for the 544-page work. “Readers will come away with a greater appreciation of who Oprah really is beyond her public persona and a fuller understanding of her important place in American cultural history,” said Crown publisher Tina Constable about the forthcoming bio.