by Conydon A Lattès, $14.95. Many people, beginning with Napoleon himself, have considered his death suspicious. Recently the research of Sten Forshufvud, a Swedish dentist with an interest in both the emperor and poisons, established beyond doubt that Bonaparte was deliberately murdered. The authors of this book go a step further. Working with Dr. Forshufvud, they undertake to discover who managed the murder. Since Mr. Weider and Mr. Hapgood have gone to great trouble to construct their account of Napoleon’s last days and Dr. Forshufvud’s investigation in the manner of a mystery story, concealing the poisoner’s identity as long as possible, it would be unfair to reveal anything of their work beyond the simple fact that it is mightily interesting if not, in the end, totally convincing. There remains one small possibility that the authors never consider.and .