The Black Widow Next Door: Audrey Marie Hilley

After poisoning her husband, daughter AND daughter-in-law with arsenic, "red collar Black Widow" killer Audrey Marie Hilley vanished without a trace. By the time police caught up with her she had created a fake identity, married a new husband, faked her own death and then come back to town pretending to be her (fictional) twin sister. This episode is a deep dive into the psychology of a cold-blooded killer who looks like the girl next door.