Investors Sue Dean Witter, Alleging Misrepresentation: In the lawsuit filed in Los Angeles County Superior Court, the Wall Street firm was accused of duping tens of thousands of investors into placing risky bets on commodities and currency futures. The investors say they lost millions of dollars in the early 1990s by buying $1.2 billion in Dean Witter Reynolds Inc.'s limited partnerships that invested in these volatile financial securities. Dean Witter spokesman Timothy Lee said it is against the firm's policy to comment on lawsuits. The lawsuit is the latest twist in the legal fight arising from the sale of billions of dollars in limited partnerships in the 1980s and early '90s. The suit, which seeks class-action status, is the first major suit to allege wrongdoing involving commodities and currency futures.