Josh Howard, executive producer of “60 Minutes Wednesday” when it aired a flawed report on President Bush’s National Guard service, resigned Tuesday, CBS said.

In the wake of the report, based on documents that were not authenticated, CBS in January fired producer Mary Mapes and asked three other news staffers to resign. Mr. Howard, who had assumed the executive producer post shortly before the report aired, was the last to leave CBS.

Separately, St. Martin’s Press acquired the rights to a book Ms. Mapes is writing about what happened at the network.