posture during the demonstration, dubbed the "Rose Mary Stretch", caused many political commentators to question the validity of the explanation. In a grand-jury interview in 1975, Nixon said that he initially believed that only four minutes of the tape were missing. He said that when he later heard that 18 minutes were missing, "I practically blew my stack." In his 2014 book The Nixon Defense, Nixon's counsel John Dean suggests that the full collection of recordings now available "largely answer the questions regarding what was known by the White House about the reasons for the break-in and bugging at the Democratic National Committee headquarters, as well as what was erased during the infamous 18 minute and 30 second gap during the June 20, 1972, conversation and why." A variety of suggestions have been made as to who could have erased the tape. Years later, White House Chief of Staff Alexander Haig speculated that the erasures may conceivably have been caused by Nixon himself. According to Haig, the president was "spectacularly inept" at understanding and operating mechanical devices, and in the course of reviewing the tape in question, he may have caused the erasures by fumbling with the recorder's controls, though Haig could not say whether the erasures had occurred inadvertently or intentionally. In 1973, Haig had speculated aloud that the erasure was caused by an unidentified "sinister force." Others have suggested that Haig was involved in deliberately erasing the tapes with Nixon's involvement, or that the erasure was conducted by a White House lawyer. Investigations Nixon himself launched the first investigation into how the tapes were erased. He claimed that it was an intensive investigation but came up empty. On November 21, 1973, Sirica appointed a panel of persons nominated jointly by the White House and the Special Prosecution Force. The panel was supplied with the evidence tape, the seven tape recorders from the Oval Office and Executive Office Building and the two Uher 5000 recorders. One recorder, labeled as Exhibit 60, was marked "Secret Service" and the other, Exhibit 60B, was accompanied by a foot pedal. The panel determined that the buzz was of no consequence and that the gap was the result of an erasure performed on the Exhibit 60 recorder. The panel also determined that the recording consisted of at least five separate segments, possibly as many as nine, and that at least five segments required hand