Who wrote "Unmasked: The Final Years of Michael Jackson" which became number one on the New York Times' bestsellers list in 2009?

Explanation

"Gone Too Soon" is a documentary film about the final year of Michael Jackson's life and career. It was released on June 25, 2010, exactly one year after Jackson's death. The documentary was produced and directed by the author and filmmaker Ian Halperin. He also who wrote "Unmasked: The Final Years of Michael Jackson", which became number on the New York Times' bestsellers list in 2009.