Tiffany Cole spied on an elderly couple plotting a way to kill them and take their money. Teresa Lewis used a combination of sex and money to manipulate two men into killing both her husband and stepson in order to gain gain $250,000 in a life insurance scheme. Brenda Spencer predated the killings at Columbine and Parkland as she went on a shooting spree at the school directly in front of her home. Kimberly Saenz hated her job as a nurse and proceeded to dispose of patients she didn't like. Nikki Reynolds was a troubled teen who eventually had a murderous run-in with her adoptive mother who loved her so much...