Despite what most Hollywood movies depict, the real-life witness protection program is highly successful. In fact, since it's establishment in 1971, the program has had 100% success rate with it's members' new identities.
The Witness Protection Protection program was put into place to protect threatened witnesses during before or after a trial in which their safety might be in jeopardy.
Out of the 9900 family members and 8500 witnesses, none have been harmed during the program's history. Most witnesses, ironically, are criminals whose names, identities, and locations must be changed in order to save them from potential harm.
Once witnesses enter the program they are given the appropriate documents, job training, money for basic expenses, as well as health care in order to live a new and productive life.
While some might think this drastic change is a mandatory assignment, witnesses actually enter the program voluntarily and are free to leave at any time and return to their old identities (although it is highly discouraged).