One of the great political mysteries — what was said by President Nixon during a suspicious 18-minute gap on the Watergate tapes — could soon be solved thanks to a keen-eyed amateur sleuth and modern crime-fighting technology.

The missing section of a 79-minute conversation between Nixon and his Chief of Staff, H. R. “Bob” Haldeman, was erased. It had been recorded during a meeting on June 20, 1972, three days after operatives connected to the White House broke into the headquarters of the Democratic National Committee in the Watergate complex.

The U.S. National Archives, which holds the Watergate files, has tried to fill in the blanks. In 2001 it set up a panel to see if new technology could bring back what was said on the tape, but nobody could.

An amateur Watergate sleuth, however, has convinced the archives that there could well be another way to solve the puzzle: using notes taken by Haldeman at the meeting.

Haldeman was a meticulous note taker who wrote in longhand on yellow legal notepads.

Phil Mellinger, a former analyst at the National Security Agency who has delved into the notes, reports, testimony and evidence relating to Watergate, said he had a “eureka” moment in October last year when he visited the National Archives and asked to see Haldeman’s notes from the June 20 meeting.

An assistant brought them out but there were only two pages. They had four sets of holes in the top left-hand corner, suggesting that staples had been taken out and new ones inserted later.

“Wow — I suddenly realized that at the top of page two, the discussion of Watergate was ending,” Mellinger told The Times of London, “The first page of notes went right up to the time they started discussing Watergate. I believe page two was about the last minute of the 18-minute discussion.”

Mellinger believes that in 1973, when the Watergate scandal began heating up, Haldeman destroyed the pages that covered the gap in the tape, then re-stapled the remainder.

Mellinger has convinced the archives to subject the existing notes to electrostatic detection analysis, which can capture indentations on paper. The hope is that what was written on the allegedly missing pages can be recreated.

Haldeman usually wrote in felt tip pen but on this day he used a ballpoint, greatly improving the chances of success. “I’m pretty confident this will work,” Mellinger said.

Click here for more on this story from the Times of London.