The 2007 documentary features interviews with:
* Keith Hunter Jesperson: The "Happy Face Killer" who admitted to killing at least eight women in the 1990s.
* Mark Hacking: A man accused of murdering his wife and staging her disappearance.
* The families of the victims: These individuals share their stories and experiences with the media.
It's possible you are thinking of a different film or documentary. If you can provide more information, I may be able to help you further.