Call 911 if there is an immediate emergency or active threat
Contact your local FBI field office
Use the FBI tip line at 1-800-CALL-FBI (1-800-225-5324)
Submit a tip online through the FBI website
Contact the nearest U.S. Embassy or Consulate if you are outside the United States
Mail correspondence to FBI Headquarters: 935 Pennsylvania Avenue, NW, Washington, DC 20535, USA