Old sins indeed -- a murdered corpse is discovered buried beneath the slave quarters on the grounds of Thomas Jefferson's storied home. Who is the mystery man wearing a gold ring and carrying $50, the newest coin dated 1803, in his pocket? And what was such a well-to-do victim doing in the slave quarters in the first place? Local gossips Mary Minor (Harry) Haristeen, Miranda Hogendobber, and Susan Tucker are aided and abetted in their juicy, harmless speculations not only by the parallel lucubrations of Harry's pets, Mrs. Murphy (feline) and Tee Tucker (canine), but by Monticello archaeologist Kimball Haynes's enthusiastic researches into Jefferson's family tree. But then Kimball himself is killed, and the variously chastened survivors, from Mira Sanburne, the mayor's fearsome helpmeet, to Samson Coles, the realtor who covets his neighbor's wife, begin to wonder how his murder could be connected to the two-centuries-old crime -- or to another homicide a mere 45 years past. The arch menagerie created by Brown and her purring coauthor (Rest in Pieces, 1992, etc.) offers an obvious bonus for cat lovers -- who will especially welcome the dozen pen-and-ink drawings of the higher species -- but her historical reconstruction, though never exactly compelling, is clever and conscientious enough to tide even ailurophobes over the rough bits.