The video of a real life killer that inspired Killing Eve's Villanelle.

Speaking to the camera in her black-and-white striped jail uniform, convicted murderer Angela Simpson is calculated and articulate as she proudly talks about her crime.

The Arizona woman was sentenced to life in prison for locking a man in her basement and torturing him for three days before finally killing him.

In August 2009, 46-year-old Terry Neely left an assisted-care facility in his motorised wheelchair. While out, Simpson lured him to her apartment by promising drugs and sex.

Once there, she attacked him and tortured him for three days. During this time she pulled his teeth out, drove a nail into his head and stabbed him around 50 times.

Three days later, firefighters were called to a residential trash bin on fire. Neely’s remains were inside.

In a YouTube video discussing her crime, Simpson said she wished she’d kept him alive for longer so she could’ve tortured him for a week.

She claimed he was a “snitch” for police – which was not true – and that he got what he deserved, but expressed regret that her arrest meant she wouldn’t be able to kill more “snitches”.

The video of her jailhouse interview is nothing short of disturbing, but for Phoebe Waller-Bridge, the creator of hit TV show Killing Eve, it was also a source of inspiration.

She told the New York Times that in the video she spied "gold dust".

In an attempt to get into the mind of the show's assassin Villanelle, played by Jodie Comer, Waller-Bridge "fell into a Google hole around female assassins", during which she discovered Simpson's 2012 interview on YouTube.

It was in this video that she discovered the key to Villanelle's mind: "[Simpson] sounds more like a psycho than anyone has ever sounded."

But then, when Simpson thinks the camera has been switched off, her whole demeanour changes.

She beams at the camera crew: "That's going to be wicked! Make it look good, please!" she says.

To Waller-Bridge, she sounded "so girlie".

It was Simpson's ability to switch so quickly that inspired the character of Villanelle's ability to jump between ruthless killer and youthful prankster.

Killing Eve is based on Luke Jennings' Codename Villanelle novellas, but Waller-Bridge was also inspired by the Simpson interview, true crime podcast My Favourite Murder and a 2016 KENZO perfume ad when writing main characters Eve and Villanelle, according to the New York Times.