IT IS NO GREAT surprise that Secretary of Labor Marshall refused to testify publicly on the current status of the government's investigation of the major pension fund of the Teamsters Union. The investigation and the negotiations with the trustees of that fund seem to be at a critical point last Sunday, the Labor Department announced that four more trustees of the fund will resign soon and that its management will be placed in the hands of outside financial institutions.If Secretary Marshall can pull this off without going into court, he will have saved the government a long and costly legal battle. He is entitled to try to do that without exposing his hand although he should realize that the deal he makes must be fully aired eventually.

The government must pursue two quite different goals in its probe into the operations of that pension fund. The first is to ensure that the fund's future management will attempt to enhance, not jeopardize, the pensions it is supposed to be able to pay to individual teamsters. The second is to determine if anyone has committed any crimes in the management of the fund's $1.4 billion in assets.

The testimony given by the fund's executive director on Capitol Hill Monday supports part of what the fund's critics have been charging for years -- that its assets have not been managed in the best interests of those who are depending upon it for their pensions. That will soon come to an end if the terms of the agreement the Labor Department says it has negotiated with the old trustees are carried out. That agreement takes effective control of the fund's assets away from labor and management officials and places it in the hands of financial institutions.

This agreement to set the fund's future course in the right direction, however, must not dissuade the government from looking further into some of the past activities of the fund. If the trustees or officers of the fund -- individually or collectively -- have done things that broke the law or opened themselves to legal liability for breach of trust, the reformation of the fund should not bar legal action against them. The questions that have been raised with respect to the administration of this fund for so long cannot be put to rest merely by improving its future operations.