truTV: Not Reality. Actuality.

He didn't know why he had killed the young man whose name he could not now recall; he hadn't wanted him to leave. Nilsen had spent Christmas alone, but now he had company for New Year's.

Scott Peterson killed his wife Laci on Dec. 24, 2002. Now, a look back in photos at his sentence.

His killing spree began on December 29, 1977. Known as the Vampire of Sacramento, Chase would consume his victims' blood to replenish his own.

On Dec 25, 1996 this child was found murdered in her home. Police pursued the parents as suspects to the exclusion of all other leads. Still unsolved, this case ranks as one of the most spectacular failures of criminal investigation.

On December 23, 1990, Canada's "Ken and Barbie sex killers" took their first victim: Homolka's teenage sister, whom they sedated in a sadistic and fatal sexual assault.

From Mary Kay Letourneau to Kelsey Peterson: a sampling of some of America's most famous female pedophiles.

Lisa Michelle Lambert murdered Laurie Show with the help of her friends and tied the Pennsylvania justice system in knots for years.