This week Denae tells Kim the story of Black Widow, Stacey Castor and how her story was part of why anti-freeze is now required to have a bittering agent. 

Sources: 

Forensic Files Season 14 Episode 7: Freeze Framed

Stacey Castor - Wikipedia

Timeline of 'Black Widow' Stacey Castor's shocking crimes - ABC News by Allie Yang, Keturah Gray, and Jon Meyersohn

Antifreeze deadly sweet taste is now gone | Lifestyles | marshallnewsmessenger.com by Laverne Hughey

Lynn Turner (murderer) - Wikipedia.