Until I Kill You viewers have criticized the final episode of the ITV thriller.

In Tuesday’s episode, fans witnessed Delia Balmer being attacked and harassed by serial killer John Sweeney.

Delia managed to move on with her life after leaving the hospital with life-changing injuries, but Sweeney was still at large and police had failed to find him for several years.

It took seven years for Sweeney to be arrested after the 2001 attack.

Viewers couldn’t believe it took this long to catch the serial killer, prompting X (formerly Twitter) to say it was ‘a total joke’.

Until I Kill You viewers called the moment the lead star was ‘badly let down’ in the final episode of the ITV thriller ‘absolutely a joke’

On Tuesday’s episode, fans witnessed what happened after Delia Balmer was attacked and harassed by serial killer John Sweeney.

One person wrote: ‘Till They Kill You is a horrific true story that shows the mistakes made by the police and justice system but the worst part is NOTHING CHANGES. ‘The police still don’t listen to women who are being harassed and stalked, and the courts still give the offender more rights than the victim.’

Another said: ‘Delia is right she is so badly disappointed she would probably be released again.’

‘They left Him in every way possible Until They Kill You,’ echoed a third.

A fourth wrote: ‘How was he allowed back into the country without withdrawing??! ‘The judicial system is completely screwed!’

A fifth added: “Police are completely incompetent in this case #untilikillillyou.”

The series was first shown on Sunday and was watched glued to the screens.

Until I Kill You follows Miss Balmer, one of Sweeney’s ex-girlfriends, who seeks justice for the attacks her ex-boyfriend suffered.

The synopsis of the series is as follows: ‘In 1991, Delia leads a wandering and lonely life, working as an agency nurse in London. When she meets free-spirited John Sweeney at a local bar, it seems like that’s the connection she’s looking for.

Fans visited X and shared their thoughts on the latest episode

The new series stars Anna Maxwell Martin as Delia Balmer, inspired by Balmer’s book about living with serial killer John Sweeney.

‘As the relationship develops, Sweeney’s artistic, anti-establishment personality gives way to a darker side, culminating in a series of violent attacks on Delia; During this attack, Delia tells him that he killed his ex-girlfriend and dumped her body in a canal in Amsterdam.

‘Sweeney was arrested but released on bail because the court failed to realize how dangerous he was.

‘He immediately pursues Delia and subjects her to a horrific, near-fatal attack.

‘He survives, but Sweeney evades capture and disappears.’

Sweeney returns seven years later and is arrested for the murder of another girlfriend (31-year-old Paula Fields) in north London.

This leaves Ms Balmer forced to confront her tormentor in open court because her testimony was ‘vital to the case against her’.

Agency nurse Delia meets John, who confesses to killing his ex-girlfriend and attacks her before escaping capture.

Sweeney was sentenced to life in prison for the murders of Fields and another woman, Melissa Halstead, whose body was found in a canal in Rotterdam in 1990.

Discussing the role, Evans told the Radio Times: ‘The story we are telling takes place over about 15 to 20 years, through the life of a woman called Delia Balmer.

‘This is essentially about how this woman fell victim to coercive behaviour, extortion, domestic abuse and violence in one of her personal relationships.

‘Ultimately, she was let down by the judicial system until they needed her as the linchpin in their case against the man. That’s basically the gist of the story.’

Till I Kill You is now available to watch on ITVX.