Federal authorities are trying to figure out how many people had money stolen in the largest identity fraud case in U.S. history.
Investigators in New York said an insider at a software company sold access to the credit histories of 30,000 people to at least 20 others.
Some victims have already reported losing money from their bank accounts, seeing their credit cards hit with unauthorized charges, and having their identities assumed by strangers.
But prosecutors said many people may not yet know they were defrauded. They're urging consumers to pay closer attention to their financial statements and credit histories and learn how to protect themselves through the Federal Trade Commission's Web site.
Those whose credit histories were stolen are receiving letters with offers of help.