Robert Owen testified Monday that Oliver North predicted as early as 1984 that he would be the "fall guy" should secret efforts to arm the Nicaraguan rebels ever become public.

U.S. District Judge Gerhard Gesell also made the first public ruling on the secrecy matters that threatened to derail North's trial two weeks ago, instructing lawyers and witnesses to substitute the name of a CIA official with "high-level CIA official No. 1" during the proceedings.Testifying for a second day at North's criminal trial on charges arising from the Iran-Contra affair, Owen - North's courier to rebel leaders - said CIA Director William Casey was in frequent touch with North when the retired Marine officer was a staff member at the National Security Council.

The boyish Owen, 35 - a staff member to Dan Quayle when the Republican vice president was the junior senator from Indiana - said Friday he ferried maps, tactical advice and thousands of dollars from North to Contra rebel leaders at a time when U.S. aid to the guerrillas was banned.

Owen told the jury that in the spring of 1984, North said he "was to be, in essence, the point man. . . . He would be the fall guy for the administration."