According to www.socialsecurity.gov
To report identity theft, fraud, or misuse of your Social Security number, the Federal Trade Commission (FTC), the nation’s consumer protection agency, recommends that you take the following steps:
Step 1: Place a fraud alert on your credit file by contacting one of the three companies:
The company you contact is required to contact the other two, which will then place an alert on their versions of your report.
Step 2: Review your credit report for inquiries from companies you have not contacted; accounts you did not open; and debts on your accounts that you cannot explain.
Step 3: Close any accounts you know, or believe, have been tampered with or opened fraudulently.
Step 4: File a report with your local police or the police in the community where the identity theft took place.
Step 5: File a complaint with the Federal Trade Commission online or by calling them at 1-877-438-4338 (TTY 1-866-653-4261).
reference: www.socialsecurity.gov, retrieved February 14, 2012 from http://ssa-custhelp.ssa.gov/app/answers/detail/a_id/329/~/identity-theft,-fraud-or-misuse-of-my-social-security-card