"This privacy incident involved the release of personally identifiable information (PII) contained in the DHS OIG [Office of Inspector General] case management system and affects two groups of individuals," the message read.
The first group consists of "approximately 247,167 current and former federal employees" that were employed by DHS in 2014, the message explained.
30 November 2017, 01:22 GMT
The second group is comprised of individuals, including subjects, witnesses and complainants associated with the department’s inspector general investigations from 2002 through 2014, the message said.
The theft was traced to a former DHS employee, who was caught with the data stored on a memory device, and not the result of an outside hacker, the message revealed.
Those affected have been offered 18 months of free credit monitoring, according to the message.
