Prosecutors Step Up Probe of Milberg Weiss Law Firm.

Reports on the federal investigation of Milberg Weiss, a U.S. class-action law firm, and one of its litigators, William S. Lerach. Immunity granted to two former partners, including Alan Schulman whose secret testimony was heard by a grand jury in Los Angeles; Background on the four-year investigation of whether the New York-based firm made illegal payments to plaintiffs in securities class-action lawsuits; Indication that former partners David Bershad and Melvyn Weiss could face indictment for conspiracy; Why the investigation is significant and controversial; The role of retired lawyer Seymour Lazar in the investigation.