The witness protection program is a very structured program, tightly framed, that requires individuals to, for example, relocate to areas that are possibly far away from where they've lived for most of their lives, far away from their friends and far away from their families, with a very clear understanding that they cannot go back to the initial location, because that's the location that's considered the threat area. Given that, there's a reluctance sometimes to enter the program, knowing that they cannot go back to an area where they've grown up or lived most of their lives.
On April 19th, 2007. See this statement in context.