Much evidence remains secret, covered by grand jury confidentiality and judicial protective orders.
But new glimpses into the strategies of both sides emerged in a hearing a week ago before Judge Lewis A. Kaplan in Federal Court in the Southern District of New York, and in subsequent interviews. On the prosecution's side, the court argument pointed to a government effort to build its case against Mr. Taubman with the testimony of assistants who could confirm meetings between top executives from each company. The case moved into high gear last January, after Christopher M. Davidge, the former chief executive of Christie's, came forward with documents supporting his assertion that at the behest of their bosses, he and his counterpart at Sotheby's, Diana D. Brooks, had conspired to fix customers' commission rates for much of the 90's. Mr. Davidge and Christie's have received conditional amnesty contingent on their cooperation with the investigation. Sotheby's and Ms. Brooks pleaded guilty Oct. 5.