Mealey's (July 13, 2015, 10:48 AM EDT) -- WASHINGTON, D.C. — Following an interagency forensics investigation into a recently announced cybersecurity incident that compromised the personally identifiable information (PII) of 4.2 million current and former federal employees, the U.S. Office of Personnel Management (OPM) on July 9 announced its discovery that the Social Security numbers (SSNs) of 21.5 million people were stolen from its background investigation databases (U.S. Office of Personnel Management Cybersecurity Incident Announcement, OPM)....