The theft of social security numbers and bank account data is linked to a Vietnamese man, who pleaded guilty to selling personal information.
That man posed as a private investigator. He even got hired as a contractor for a site called Court Ventures. A credit reporting service Experian bought Court Ventures last year.
One local cyber-security expert has tips on how to avoid becoming a victim.
"We need to really think about which websites we register with, which merchants we shop at. Which companies we ultimately do business with," said Eric Chiu, president of HyTrust.
Prosecutors have not said how many people actually had their sensitive data stolen.