ITV's Until I Kill You: The real life story of Delia Balmer behind the TV drama

New ITV drama Until I Kill You tells the harrowing real-life story of Delia Balmer. Set in 1991, the series follows London-based agency nurse Delia Balmer (Anna Maxwell Martin), who initially believes she has found a true romantic connection with John Sweeney (Shaun Evans), a 'fellow free spirit.'

After meeting in a Camden pub, Delia feels she shares a bond with Sweeney, a carpenter and casual laborer who also loves travelling. Liverpool-born Sweeney seems like the perfect boyfriend, often bringing Delia flowers. However, she soon discovers he is a dangerous killer who will one day turn his rage on her, reports the Mirror.

In her 2017 book Living With a Serial Killer, which informed the series, Delia reflected on his manipulative behavior: "Subtle changes happened slowly. I should've known something was wrong, but I am too soft and trusting. I'd never encountered anything like it before."

Sweeney, who was squatting, eventually moved into Delia's home. His behavior became increasingly controlling and abusive, with his furious temper alarming her. Living in constant fear, it took Delia years to gather the courage to ask Sweeney to leave, only to be met with shocking cruelty.

Although she first asked him to leave in December 1993, Sweeney continued to manipulate her, with his abusive behavior escalating in the spring of 1994. Over several days, Sweeney held Delia captive, restraining her to a bed and threatening to mutilate her tongue if she screamed.

During this ordeal, Sweeney confessed to murdering his ex-girlfriend, model and photographer Melissa Halstead, whose remains were found in a Rotterdam canal in 1990. In her book, Delia recalled Sweeney's chilling words: "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, put them in bags, and threw them in the canal."

Fearing for her life, Delia carefully avoided provoking Sweeney, and he eventually released her. She later reflected: "He was very quick, and if I had tried anything, I probably would have ended up cut up." Unfortunately, Sweeney continued to stalk and attack her, culminating in a brutal axe assault that left Delia severely injured.

Sweeney fled the scene and evaded police for years. During this time, he murdered Paula Fields, a mother of three, in 2000 and discarded her body in London’s Regent’s Canal. He was finally arrested in 2001 and sentenced to nine years in prison for his attack on Delia.

While serving his sentence at Gartree Prison, Sweeney was questioned about Melissa and Paula's murders. Advances in DNA technology, combined with Delia's testimony, helped authorities build a case, leading to his conviction.

In 2011, Sweeney was found guilty of murdering both women and was sentenced to life imprisonment without parole. It is believed he may have killed three other women who were reported missing between 1970 and 1990.

Sweeney refused to leave his cell at Belmarsh Prison as his sentence was read. Sentencing him, Judge Mr. Justice Saunders stated: "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 actively involved in the making of Until I Kill You, providing feedback on the script written by Nick Stevens. Speaking with ITV, she said: "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 repeatedly, 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 and be further traumatised by the system."

Despite rebuilding her life, Delia admits that her ordeal still affects her deeply. "I often suffer from depression and anxiety, afraid of life and the future, a compulsive worrier," she shared.

"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."

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