The Fatal Flaw: A Special Edition of 20/20

A dollhouse replica of a crime scene reveals the killer of a young wife.

Firsthand accounts from authorities and journalists illuminating four disturbing events.

When Stacey Castor's husband dies of an apparent suicide, not all the pieces add up. Is Stacey a tragic widow or will an overlooked detail reveal that something far more sinister is going on?

When devoted mom Christina Harris dies from a mysterious drug overdose, her family is sure she's been murdered. Could this be the perfect crime, or will one fatal flaw give Christina's family justice?