Nixon Library director Timothy Naftali, David Paynter of the National Archives and independent researcher Phil Mellinger discuss the forensic analysis.

The most famous 18 1/2 minutes of American history remain a mystery.

High-tech detective work undertaken two years ago by the National Archives, the Library of Congress and other government agencies to find out what was erased in the Nixon Watergate tapes has come up dry, to the disappointment of history buffs.

Forensic scientists assembled by the Archives examined two pages of notes from a June 20, 1972, meeting at the White House between President Richard Nixon and Chief of Staff H.R. Haldeman, a few days after several men were arrested for breaking into the Democratic National Committee Headquarters at the Watergate office complex in Washington.

The president had a secret taping system that recorded his phone calls and conversations in the Oval Office, and these notes were believed to hold the clue to what was erased from the audiotapes in the scandal that led to Nixon’s resignation on Aug. 9, 1974.

The question of what Nixon knew about the break-in caused a national controversy when investigators discovered that 8 1/2 minutes were missing from the tapes.

Using new forensic tools, scientists studied impressions in the papers that they hoped might reveal evidence of missing notes from the conversation. But the Archives said Thursday that nothing was found.

See the full story of Watergate, Nixon’s resignation and The Washington Post here.