The horrifying true story behind ITV’s Until I Kill You

ITV’s new drama Until I Kill You tells the true story of nurse Delia Balmer’s shocking ordeal of realising her boyfriend of three years was a serial killer.

The series, based on Balmer’s 2017 memoir Living with a Serial Killer, stars Motherland ‘s Anna Maxwell Martin as Balmer andVigil actor Shaun Evans as serial killer John Sweeney. It depicts everything from the beginning of the pair’s relationship to all the moments Balmer tried to leave Sweeney, up until when he attacked her using an axe.

Balmer and Sweeney met in a pub in London’s Camden in 1991 and instantly got along when they learnt of each other’s love for travelling. Sweeney told Balmer he worked on construction sites in Germany and travelled frequently.

When their relationship began, Sweeney called Balmer regularly; he would gift her flowers and shower her with affection. Balmer later realised that these attempts at showing love were manipulative as he gradually became more controlling and physically abusive as time went on.

Writing in her memoir, Balmer remarked that the changes happened slowly at the beginning. “I should’ve known something was wrong but I am too soft and trusting. I’d never come across anything like it before,” she wrote.

Balmer attempted to get out of the relationship but she feared for her safety. She briefly left Sweeney in 1994 and changed the locks on her front door. She asked the police to investigate a suspicious bag hidden behind a bathroom panel, which she describes in the book as a “body disposal kit meant for me”.

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Despite Balmer’s attempts to warn the police, Sweeney broke into her home and held her hostage for four days, tying her to a bed and threatening her with a gun. He then confessed to murdering his previous girlfriend, 33-year-old Melissa Halstead and two men in Amsterdam (Halstead’s remains had been found mutilated in a canal in Rotterdam in 1990 but no suspect had been linked).

When Sweeney did leave the flat, Balmer fled to report what had happened to the police. They arrested Sweeney for holding her hostage but allowed him out on bail.

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Balmer returned home one day after Sweeney’s release to find him waiting to attack her with an axe. In harrowing scenes recounted in both the book and series, Sweeney cut off one of Balmer’s fingers, while a neighbour came to her rescue by striking Sweeney with a baseball bat. Sweeney escaped and went on the run.

In the subsequent trial, Balmer said: “He had the axe above his head ready to finish me off. Then the man next door came out and risked his life. I had just curled up ready to go.”

Balmer was severely injured; her arm was broken, her tendons were torn and she had a missing finger.

Sweeney was arrested in 2001 and was given four life sentences for the attempted murder of Balmer, and for having four guns when he was arrested while on the run.

In 2010, while serving this sentence, he was charged with the murder of Halstead and the murder of 31-year-old Paula Fields, who he had killed while on the run. Her body was also found in Regent’s Canal near Camden in 2001.

He was found guilty of both crimes in 2011 and sentenced to life imprisonment. According to the BBC, authorities believe he may have killed three more women who had gone missing in the area between 1970 and 1990.

When Sweeney, originally from Merseyside, was sentenced at the Old Bailey in 2011, judge Mr Justice Saunders called the murders “terrible, wicked crimes”.

“The heads of the victims having been removed, it is impossible to be certain how they were killed. The mutilation of the bodies is a serious aggravating feature of the murders,” he explained.

“Not only does it reveal the cold-blooded nature of the killer, but it has added greatly to the distress of the families to know that parts of the bodies of their loved ones have never been recovered.”

Until I Kill You begins on 3 November on ITV1.