WASHINGTON INSIDERS, especially those on the Hill, have high praise for the General Accounting Office. Behind that gray and hardly glamorous name is a formidable army of budget analysts, economists, lawyers and experts on just about every federal program. An arm of Congress -- not part of the executive branch -- the GAO is both auditor and special investigator for the legislature on matters involving the expenditure of the taxpayers' money. It has responsibilities that include the evaluation of programs, activities and financial operations of federal departments, agencies and grantees. The GAO also provides expert advice to congressional committees both in developing legislation and keeping an eye on the way it works in practice. Finally, the agency responds to requests for information and analysis from individual members of Congress. As a consequence, last year its studies ranged from foreign aid expenditures in Haiti to the sale of a surplus federal warehouse in Selby, Ohio.

So it's not as if GAO didn't have enough to do, and it's not as if it were a prosecutorial arm of government, either. That is why the question keeps arising: why was the GAO charged with investigating the possibility of criminal or improper conduct on the part of a former government employee, Michael Deaver? Yes, the GAO's experts range beyond accountants, and yes, there are a number of lawyers on the staff. But traditionally, their responsibility lies in examining government contracts, advising on the legality of proposed expenditures and settling certain claims for and against the federal government. The Deaver investigation was quite different since it did not involve public money or even a person who is now a public employee. The GAO's role is especially puzzling given that a number of other federal offices -- the FBI, the Department of Justice, the Office of Government Ethics and assorted congressional subcommittees -- were already deeply involved in the Deaver matter. In addition, the appointment of an independent counsel had been sought. Each of these has a clear objective in a case of this kind -- criminal prosecution, the enforcement of ethical codes or the drafting of new legislation to close loopholes in existing ethics laws. The GAO could only send its report on to the Justice Department.

There is no question concerning the legality of the GAO's investigation: the law requires the agency to undertake any task referred by a congressional committee -- in this case, the House Energy and Commerce Committee. But whether it is wise to send people with a special kind of expertise into a new and different field is another question. The report struck many, including us, as tendentious and unfair in its implications, the work of people who were out of their field and ill-equipped to take on an assignment requiring the greatest care in the sifting of evidence and the protection of the rights of the accused. New York Times columnist William Safire, who has himself perhaps been Mr. Deaver's toughest and most consistent critic, called the investigation "a sham" and accused its authors of "brazen sophistry." For an agency more usually described as objective, nonpartisan, diligent and effective, all this must come as an unwelcome surprise. The GAO should be allowed to get back to its own business, concentrating on the kind of investigations it does best and leave the quasi-criminal investigating to others whose experience and resources make them better suited to the task.