"My mother was like a ticking time bomb. I never knew when she would go off."

"My mother was like a ticking time bomb. I never knew when she would go off."

For years, Sami, Nikki, and Tori Knotek were tortured by their mother, Shelly. Whenever her children committed a "crime," like using the bathroom without permission, she would force them to bring her handfuls of their own pubic hair or dance naked with their boy cousin while she laughed at their shame. She once even shoved Nikki's head through a glass door.

But when their mother opened their home to houseguest Kathy Loreno in 1988, the Knotek sisters were almost relieved that their mother would now have someone else to torture. But then they watched in horror as their mother forced Loreno to sleep in the boiler room, drugged and starved her, poured bleach in her wounds, and waterboarded her. When Loreno died of her injuries in 1994, Knotek burned her corpse and threw the remains into the Pacific Ocean.

But this was just the tip of the iceberg of her horrific crimes. This is the sadistic true story of serial killer Shelly Knotek, "America's most evil mom":