ITV's Until I Kill You reveals Delia Balmer's real story and chilling relationship with killer John Sweeney

A chilling new TV drama named Until I Kill You - based on harrowing real-life events - will hit screens tonight.

The ITV series, which is set in 1991, follows London-based Delia Balmer, who is an agency nurse. Delia, who is played by Anna Maxwell Martin, initially believes she's found a true romantic connection with 'fellow free spirit' John Sweeney (Shaun Evans).

After meeting in a pub, the nurse believed she'd found common ground with the carpenter and casual labourer Sweeney, who shared her passion for travelling. On the surface, Liverpool-born Sweeney proved to be an adoring boyfriend, regularly treating the then 40-year-old Delia to bunches of flowers.

But her new lover was, in fact, a dangerous killer who would one day use his rage against her. In her 2017 book Living With a Serial Killer, which has helped inform the series, Delia, who now views his displays of affection as manipulative, recalled: "Subtle changes happened slowly. I should've known something was wrong but I am too soft and trusting. I'd never come across anything like it before."

Sweeney was homeless before he ended up moving into Delia's home. Soon, she became alarmed by his temper and his coercive and abusive behaviour. It took years for Delia to pluck up the courage to ask Sweeney to leave - and he reacted with shocking cruelty.

Although she'd first asked him to leave in December 2023, Sweeney continued to manipulate Delia, with his abusive behaviour escalating sharply in the spring of 1994. Over the course of several days, Sweeney held Delia captive in her own home, keeping her restrained to the bed, and threatening to mutilate her tongue if she screamed.

It was during this nightmare ordeal that Sweeney confessed to the murder of his ex-girlfriend, the model and photographer Melissa Halstead, whose remains were recovered from a Rotterdam canal in 1990. Remembering Sweeney's chilling words in her book, Delia wrote: "We had a room in Amsterdam. I went in. There were two Germans there with her. I killed them all. I didn't know what to do with the bodies. I sat with them for three days. On the third day, I cut them up, and I put them in bags and I threw them in the canal."

Fearing for her life, Delia was careful not to rouse Sweeney's anger further - and he eventually freed her. Delia reflected: "He was very quick, and if I had tried anything, I probably would have ended up cut up." Unfortunately, this wasn't the end of the story for Delia, and Sweeney continued to hound her, carrying out multiple vicious attacks that culminated in a savage axe rampage that left Delia with severe injuries.

Sweeney fled the scene and managed to evade police detection for years. During this spell, he he targeted and murdered mum-of-three Paula Fields in 2000, tossing her body into London's Regent’s Canal. In 2001, he was finally caught and arrested, and given a nine-year custodial sentence against Delia.

While serving time at Leicestershire's Gartree Prison for the attack on Delia, Sweeney was also questioned about Melissa and Paula, with officers suspecting a connection. Eventually, advances in DNA technology on top of Delia's testimony, helped authorities build a case against evil Sweeney, and put him behind bars for good.

After being found guilty of killing both women, Sweeney was caged for life in 2011 without any bid for parole. Horrifyingly, as reported by the BBC, it's believed Sweeney could have killed three other women who were reported missing between 1970 and 1990.

Sweeney refused to leave his prison cell at Belmarsh prison as his sentence was handed down. Judge Mr Justice Saunders, sentencing him, told the court at the time: "These were 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."

Delia was involved in the making of Until I Kill You. She offered critiques of the draft script penned by writer Nick Stevens. Speaking with ITV ahead of the series being aired, Delia shared: "When I wrote my original story, I included every detail of what happened. When it came to the final attack on the doorstep, I edited it over and over again, wanting everything to read precisely as it had happened.

"My concern has always been to get the truth out by whatever means. I remain an angry person. Sweeney was let out on bail. The police gave me insufficient protection before his final assault. Later, I was forced to go to court to be further traumatised by the system."

Although Delia has managed to rebuild her life in the aftermath of her trauma, her ordeal still affects her to this day. She explained: "I often suffer from depression and anxiety, afraid of life and afraid of the future, a compulsive worrier.

"When I look in the mirror I see a stranger. Certain physical pain, I will have for life. I am stuck. I cannot move on, and cannot go further. Fear holds me back from doing certain things. I live for travel, but it has also become almost my only escape from reality. Ballet classes have always been an important part of my life."

You can catch the first episode of Until I Kill You this evening (November 3) at 9pm on ITV1.

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