THE JURY The Attorney, which marked the return of Steve Martini's lawyer-sleuth Paul Madriani, was hailed for its "well-observed courtroom maneuverings" (The Christian Science Monitor) and "crisp dialogue and tart observations" (Publishers Weekly). Now Martini delivers the most daunting capital case of Madriani's career.   Paul Madriani has ample reason to suspect he's representing a guilty man. Dr. David Crone, a respected medical researcher and principal in mapping the human genome, is charged with the murder of a young colleague: twenty-six-year-old Kalista Jordan, an African-American research physician whose body washed up on a beach in San Diego Bay. Forensic evidence links her murder with material in Crone's garage. Crone had both opportunity and motive: Kalista had recently ended their affair, and may have been deserting him professionally as well, moving on to a rival genetic research facility. However, when a key witness for the prosecution dies unexpectedly, leaving an incriminating note behind, Crone's innocence seems confirmed-until Madriani hits upon a potentially damning loose end.