McGinniss wrote in the book about how he became convinced MacDonald was guilty of killing his then-wife and two children in North Carolina in 1970.
MacDonald had suggested the 1983 book to McGinniss but sued in 1987. He alleged McGinniss had tricked him by pretending to believe in his innocence. He received an out-of-court settlement of $325,000.
MacDonald is in federal prison in Cumberland, Md. His current wife, Kathryn MacDonald, said Tuesday this isn't a time for "negativity." She says the couple wishes McGinniss peace.
McGinniss died Monday in Worcester (WUS'-tur), Mass., of complications from prostate cancer. He was 71.