Caught on camera: The moment Sadie Hartley killers were arrested by police in dawn raids - and then led cops to the muddy field where the stun gun and knife used for the murder were buried

  • Documentary follows police investigation into murder of Sadie Hartley
  • Cameras captured the first call to the crime scene and killer's arrest
  • Murderer Katrina Walsh is seen leading officers to weapons used in attack
  • ITV film also features interviews with Mrs Hartley's daughter, Charlotte

The downfall of Sadie Hartley's murderers was caught on camera as part of a gripping behind-the-scenes documentary that will air tonight. 

Lancashire Police was being followed by a TV crew when officers received the call to the crime scene at Mrs Hartley's home in the village of Helmshore on January 14.

Cameras then recorded every stage of the investigation as detectives pieced together evidence and unpicked a web of lies before finally unearthing the truth behind the vicious killing.

The dramatic footage includes the moment killer Sarah Williams, 35, was charged with murder and when accomplice Katrina Walsh led police to the murder weapons.

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Arrest: Sarah Williams was woken by police officers during a dawn raid on her Cheshire home

Arrest: Sarah Williams was woken by police officers during a dawn raid on her Cheshire home

Questioning: Killer Katrina Walsh is interviewed by police in The Murder Of Sadie Hartley

Questioning: Killer Katrina Walsh is interviewed by police in The Murder Of Sadie Hartley

Murder weapon: Lancashire Police recover the knife used to kill Mrs Hartley from a field

Murder weapon: Lancashire Police recover the knife used to kill Mrs Hartley from a field

Police investigation: Williams, pictured right, is charged with the murder of Sadie Hartley

Police investigation: Williams, pictured right, is charged with the murder of Sadie Hartley

The Murder Of Sadie Hartley, which airs at 9pm tonight on ITV, also features interviews with Mrs Hartley's daughter Charlotte, who speaks of losing her 'hero' mother.

In one chilling scene, riding instructor Walsh, 56, is captured sobbing on the floor of the police station as she arrives to be questioned under caution for the first time. 

She claims to have a three-day memory before telling an officer that she believes her friend Sarah Williams is a 'psychopath' and had killed Mrs Hartley.

With no hint of emotion, Walsh adds: 'She wants to take Ian off the b****', referring to Mrs Hartley's partner Ian Johnson, with whom Williams had previously had a relationship.

Williams and Walsh were both convicted of murder last month following a seven-week trial at Preston Crown Court. 

Victim: Sadie Hartley, pictured, was murdered by Walsh and Williams at her Lancashire home

Emotional: The documentary also features Mrs Hartley's daughter Charlotte, 23, pictured

Emotional: The documentary also features Mrs Hartley's daughter Charlotte, 23, pictured

The jury heard that, consumed with jealousy after her relationship with Mr Johnston broke down and he rekindled a romance with Mrs Hartley, Williams attacked her love rival with a 500,000-volt stun gun and stabbed her 40 times at her home.

Evidence later revealed how she and Walsh had hatched an 18-month-long plan to kill Mrs Hartley which involved scouting her house, travelling to Germany to buy a weapon, and purchasing a second-hand car in a bid to evade detection.

Justice caught up with Williams three days after the attack and the scene was caught by production company Raw Cut TV, who made the documentary for ITV.

Ski instructor Williams was filmed sitting bolt upright in bed after being abruptly woken by the five officers sent to detain her at 3.10am on January 17. 

In custody: Murderer Sadie Williams, seen left, is led to a cell in a scene from the documentary

In custody: Murderer Sadie Williams, seen left, is led to a cell in a scene from the documentary

PC Jane Davies, who can be seen here telling her she is under arrest, would later tell Williams’s trial that at that moment ‘she appeared dazed and confused’.

In another dramatic moment, Walsh is seen leading police across a farm, pointing out where she buried the stun gun and pepper spray used in the vicious attack.

She also reveals where she left a set of car keys that are 'significant' to the investigation. 

The documentary also hears from Mrs Hartley's 23-year-old daughter, Charlotte, who says she wants her mother to be remembered as the 'happy, lovely lady she was'. 

She adds tearfully: 'This wasn't supposed to happen to her. The fact someone has taken her life for no reason whatsover is disgusting. 

'She has got two children, she has got her whole family that loves her. It is just numbing. I feel strongly that it has ruined me and my brother's life.'

Captured every moment: Cameras filmed Walsh as she was charged with murder

Captured every moment: Cameras filmed Walsh as she was charged with murder

Recovered: Walsh leads police officers to the field where she buried the stun gun, pictured 

Recovered: Walsh leads police officers to the field where she buried the stun gun, pictured 

Key evidence: An officer holds a stun gun that was recovered from the field in Cheshire

Key evidence: An officer holds a stun gun that was recovered from the field in Cheshire

Steve Warr, Executive Producer for Raw Cut TV said: 'We were privileged to get the inside story of the investigation into who killed Sadie and the story that evolved is stranger than any crime drama. 

'How these detectives hunt down the two women at the heart of the murder is utterly compelling and the most complete and gripping picture of a real life crime being solved I have ever seen.'

Sue Murphy ITV's Head of Factual Entertainment said: 'This unique documentary takes the viewer behind the walls of the police station to show how the detectives involved set about solving this incredibly complex crime and gets under the skin of the officers to reveal their inner thoughts and emotions. 

'Rich in detail and totally compelling, the film never loses sight of the fact that at the centre of this tragic story is a violent act which strikes at the heart of a loving family.'

The Murder of Sadie Hartley is on at 9pm on ITV on Thursday 1 September  

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