Former Navy Secretary James H. Webb says he learned last fall of a massive fraud investigation and deliberately kept Defense Secretary Frank C. Carlucci in the dark, figuring the FBI would tell him when it wanted to. Webb, in a telephone interview Tuesday, also said he was told from the start that former Navy official Melvyn R. Paisley was a ``central figure'' in the probe and that a member of his headquarters staff was under scrutiny. Webb said he wasn't told and didn't ask the identity of the official on his staff under investigation. FBI search warrants suggest the Navy official is James Gaines, the deputy assistant secretary for acquisition management. Webb said he never attempted to discuss the matter with Carlucci because ``that wasn't my job.'' ``This was a very close-hold report involving an investigation being conducted by the FBI with the NIS (Naval Investigative Service) cooperating, not the Department of Defense,'' he said. ``My view was that if the FBI wanted to tell Carlucci, they would tell him. How should I know whether they wanted to tell him? Why should I get tangled up in all that?'' Pentagon spokesmen have said Carlucci did not learn of the probe until June 13, the day before FBI agents began executing search warrants at the Pentagon and elsewhere around the country. The former Navy chief added he was originally told the investigation would probably be completed by last Christmas, ``but it kept getting delayed because the net kept expanding.'' Webb, a Vietnam War hero, lawyer, novelist and former assistant defense secretary, became the secretary of the Navy in April 1987 after the resignation of John F. Lehman Jr., who had held the post for six years. Paisley was an assistant secretary of the Navy and one of Lehman's top aides. He left at the same time Lehman did and established a defense consulting business. ``I was, in fact, briefed about this last fall,'' Webb said. ``And I was then periodically updated on it by the chief of the Naval Investigative Service. ``I was told that with respect to the Navy, Paisley was the central figure. I was also told an individual still on my staff was under investigation.'' After the briefing, Webb said, he did two things. ``I told them I didn't want to know who it was on my staff, but please try to hurry up and get the investigation done if that was the case,'' Webb said. ``I didn't like the idea of someone committing felonies when I'm trying to reorganize (with new people). ``And I also asked the NIS to communicate to the FBI my concern that if they were investigating Paisley, it be for substantive matters because of Paisley's relationship with Lehman. I didn't want it to appear to be a witch hunt.'' According to the Justice Department, the NIS began the current investigation two years ago and then called in the FBI. Justice officials say the inquiry centers on allegations that Pentagon executives took bribes from private military consultants who were seeking classified contract information for defense contractors. Webb said his knowledge of details of the investigation always was limited. Asked if he was told there were other ``central figures'' working for other armed services or on the Pentagon staff, Webb replied, ``No comment.'' Webb also said that long before he knew of the investigation, he canceled a consulting contract between Paisley and the Navy that allowed Paisley to keep his security clearance for super-secret ``black'' program information. The consulting arrangement was established shortly before Webb took over as Navy secretary. Webb said he canceled it as soon as he learned of its existence, less than a week after assuming office. ``The arrangement kind of bothered me, the access to black information (for a consultant),'' Webb said.