St. Louis Employees Retirement System yesterday began searching for its first S&P 500 index fund manager to run $62 million and expects to interview finalists at its May 25 board meeting, said William Duffe, director for the $475 million fund. No RFPs will be issued; instead all proposals will be handled by Mr. Duffe. "I would like to start receiving proposals as soon as possible, he said. Funding will come from terminating Mississippi Valley Advisors as a core large-cap U.S. equity manager, he said. Performance is not an issue, he added.