Memo Helps Plug Gap in Watergate Puzzle : Scandal: The infamous erasure of an Oval Office tape recording by President Nixon’s secretary was no accident, a newly released document suggests.

One of the abiding mysteries in the scandal that brought down former President Richard Nixon is how part of a crucial Watergate tape came to be erased before the White House relinquished it to federal prosecutors.

The erasure, popularly known as the 18 1/2-minute gap, was admitted by Rose Mary Woods, the former President’s personal secretary and confidante, who insisted in 1973 court testimony that it was accidental. Woods said that she had depressed a foot pedal for several minutes inadvertently while talking to a friend on the telephone--an explanation prosecutors regarded as preposterous but could never disprove.

Now a new document from Woods’ personal files, released Thursday by the National Archives among 270,000 additional pages of Nixon materials, suggests that the erasure was deliberate. But the document itself seems almost as mysterious as the gap.

Dated Jan. 10, 1974, but unsigned, the typewritten document with no letterhead reports that Nixon White House lawyers Leonard Garment and J. Fred Buzhardt told two months earlier of “their client Miss Woods intentionally, not accidentally, erasing 18 1/2 minutes of the June 20, 1972 tape” of a conversation about the Watergate break-in between Nixon and his chief of staff, H.R. Haldeman.

The 13-page memo, headed “Memorandum to Research Staff,” said that Garment and Buzhardt also advised Watergate special prosecutor Leon Jaworski and U.S. District Judge John J. Sirica, who subsequently conducted a hearing on the erasure, that “there is no innocent explanation of the gap or erasure.” The two lawyers implied that Woods might be guilty of obstruction of justice--since the tape was under subpoena--and they arranged for her to be represented by an outside attorney, the memo said.

Karl Weissenbach, a deputy archivist who has helped organize the Nixon files, said that he does not know who authored the memo. “We’re not entirely sure it is a White House document,” he said, although it was found among Woods’ files.

Garment, now a Washington attorney, said that he recalled telling Jaworski and Sirica--both of whom are dead--that he believed there was “no clear-cut innocent explanation” for the erasure, which Woods said occurred while she was transcribing the White House recording.

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Garment said that he and Buzhardt, who also has died, avoided questioning Woods directly because they did not think that they could properly represent her interests while continuing to represent Nixon’s. But after she retained Charles Rhyne as her private attorney, Garment said he came to accept Woods’ sworn testimony in court that the erasure was accidental or was the result of a mechanical malfunction. Neither Rhyne nor Woods could be reached for comment.

Richard Ben-Veniste, an associate Watergate prosecutor who questioned Woods in open court, said that he recalled an earlier visit to his office by Buzhardt. “He was pretty shaken,” Ben-Veniste said. “He said he realized this tape was under subpoena by our office and he knew of no innocent explanation for the gap.”

Ben-Veniste, now a Washington-based defense attorney, said that the new memo only strengthens his conviction that the erasure was deliberate. If that could have been proven, he said, Woods or other White House aides would have been indicted for obstruction of justice.

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When Woods came to Sirica’s court to testify in November, 1973, she did not know “that her (White House) attorneys had made the crime charge to the court in secret session,” the memo says.

Woods was ordered by Sirica to demonstrate for a photographer how she claimed she had to stretch to reach her telephone while keeping one foot on the tape machine’s pedal. The photo, widely circulated by the press, was dubbed “the implausible stretch” by Ben-Veniste.

Sirica later asked a panel of outside technical experts to study the erased tape along with Woods’ transcription equipment. The panel reported on Jan. 15, 1974, that the entire erasure had been caused by a sequence of five to nine separate erasures. But the experts stopped short of characterizing the act as deliberate.

The new files released by the archives represent a continuation of its effort to make public all of the Nixon Administration’s papers and tape recordings once they have been catalogued, indexed and screened to omit private medical matters or papers that could affect national security.