The drive disappeared from a processing room at the National Archives and was last seen sometime between October 2008 and the first week of February; officials realized it was missing around March 24. The loss was discovered when the processing office apparently wanted to do an analysis on the drive to see if an automated tool could be used to validate the data it contained. The validating of data until then had been done by staff members who were reassigned to other projects in March.

It is still unclear whether the drive was misplaced or stolen. But the NARA has added new physical controls over archived records, revamped office access measures and updated processes for handling personally identifiable information. A criminal investigation has also been launched by the NARA's office of the Inspector General and the FBI.

News of the missing drive sparked some concern among lawmakers who were briefed on it Tuesday by the NARA's inspector general. Rep. Darrell Issa, (R-Calif.), ranking member of the House Committee on Oversight and Government Reform, in a statement issued yesterday, called it an "egregious breach" that raised significant questions about the effectiveness of the security controls in place at the Archives. Issa said that the NARA's inspector general had told the committee that the hard drive had gone missing in an area where at least 100 employees and numerous janitors, visitors and interns had access to it.

Meanwhile Rep. Edolphus Towns, (D-N.Y.), chairman of the House Oversight and Government Reform Committee, said he would be holding briefings on the ongoing investigations to "begin to understand the magnitude of the security breach."