Piers Morgan travelled across the Atlantic to meet some of America's most notorious female murderers and won praise for his sensitive approach to a difficult subject.
In the first episode of ITV's Killer Women, Good Morning Britain's Piers travelled to Texas to meet Erin Caffey.
At the age of 16, she masterminded the brutal murder of her entire family, but her father survived. Erin will remain behind bars until she is almost 60 years old for conspiring with her boyfriend to kill her mum, dad and two younger brothers.
Viewers who watched took to Twitter to express their admiration of Piers, and their shock at Erin's actions.
Praise for Piers
Not normally a fan of Piers Morgan, but damn, he's good! #KillerWomen
-- Abbey (@abbeymcd_xo) May 11, 2016
-- Daisy Date (@daisy_date) May 11, 2016
-- Aaron Dodds (@AaronDodds1) May 11, 2016
-- Melissa Hardwick (@mellieh75) May 11, 2016
-- Dave / DKS (@DavidMackayy) May 11, 2016
Disbelief at Erin
Erin is a cold hearted killer. This was her family. I am in shock. #KillerWomen
-- Emily Jayne (@loveemilyjayne) May 11, 2016
Genuinely fascinated watching this. The fact Erin can be so calm and relaxed is just so scary #KillerWomen
-- claire (@clairestead222) May 11, 2016
-- Harriett Ferris (@harriett_ferris) May 11, 2016
Erin is a bit odd. She's very emotionless and has shown no remorse for someone who claims to be upset. #KillerWomen
-- Kayles? (@_IamKayleigh) May 11, 2016
Erin Caffey is truly terrifying. Her eyes are ice cold. #KillerWomen
-- Code_Curly (@Curly_Nics) May 11, 2016