United States Federal Witness Protection Program

The United States Federal Witness Protection Program (WPP), also known as the Witness Security Program or WITSEC, is a witness protection program. It is operated by the United States Marshals Service. It was created to protect threatened witnesses before, during, and after a trial.
A few states, including California, Connecticut, Illinois, New York, Texas, and Washington D.C. have their own witness protection programs for crimes not covered by the federal program. 
The state-run programs have less protections than the federal program.