At 76, and after more than 20 published books, all things morbid continue to fascinate Seattle’s own Ann Rule, America’s most prolific true-crime writer. She’s now decided to tackle the subject of Josh Powell and the horrific story of how he came to kill himself and his two small boys in a gasoline-fueled blaze earlier this month. The book will also deal with Susan Cox Powell, the wife who mysteriously disappeared from their Utah home more than two years ago.Rule, best known for The Stranger Beside Me, about the notorious serial killer Ted Bundy — whom she met many years ago at a local crisis counseling center where she worked — plans to meet today with the boys’ grandparents, Chuck and Judy Cox, reports the Tacoma News Tribune.Rule could not be reached for comment this morning, but Chuck Cox said it is unclear whether the family will profit from the author’s latest endeavor. Cox did say, however, that Rule pledged to make a contribution to the Susan Cox Powell Foundation.Cox told the News Tribune, “We don’t have any desire to make money on anything,” adding that Rule had begun research on the book before his grandsons, Charlie, 7, and Braden, 5, were killed.Cox said the book may help bring attention to the case and what might have gone awry during the probe into his daughter’s disappearance — as well as delving into possible shortcomings by Washington child-welfare agencies.Follow The Daily Weekly on Facebook and Twitter.