Googled: Witness Protection Program, Maintaining False Identity, Creating a false identity
(Can you tell my Googling skills are less than awesome?)
More than anything, I'm interested not so much in the actual creation process involved, as the process of maintaining the second identity and not "breaking character," as well as the psychological effects of maintaining multiple personas for many years. I found a few references to the dissosiative orders that secret agents suffer, but nothing particularly enlightening.
Thanks in advance for your help!