A SCORNED woman assassinated her love rival with “demonic savagery” after plotting the killing for 17 months, a court heard yesterday.

Sarah Williams, 35, is accused of paralysing mum-of-two Sadie Hartley with a cattle prod and then knifing her 40 times in her home.

8 Sarah Williams, pictured, and pal Katrina Walsh are charged with the murder of Sadie Hartley Credit: Guy Patrick

Williams is said to have planned the murder with best pal Katrina Walsh, 56, in a plot described as “the stuff of spy novels”.

The pair are even said to have discussed planting an IS flag at the scene to mislead cops.

Williams allegedly bought a tracker in order to find out where her ex, Ian Johnston, 57, was living with new partner Sadie, 60.

She stabbed and slashed this unfortunate woman – blow after blow – causing appalling and fatal injuries John McDermott QC

8 Businesswoman Sadie was knifed to death at her home in the village of Helmshore, Lancashire in January this year Credit: CHRIS NEILL/MAVERICK PHOTOGRAPHY

After a number of reconnaissance missions, including a chilling test run where Walsh delivered flowers to Sadie, the pair are said to have waited until Mr Johnston was away on a ski trip.

John McDermott QC told Preston crown court Williams turned up at Sadie’s £500,000 home in Helmshore, Lancs, in January 2016.

He said: “What happened next is truly shocking. Sarah Williams stood on the doorstep.

8 Accomplice... Katrina Walsh, 56 Credit: Guy Patrick

“As soon as the door was opened she lunged at Sadie Hartley with a cattle prod.

“She pressed it against Sadie Hartley’s head and incapacitated her. Then, with what can only be described as demonic savagery, she attacked her with a knife.

“She stabbed and slashed this unfortunate woman, blow after blow, causing appalling and fatal injuries. At least 40 knife injuries.

“She left her in a pool of blood in the hallway, closed the door, walked back to the car and set off back to her home.

8 Ian Johnstone with partner Sadie Hartley who was later stabbed to death in her own home Credit: PA:Press Association

“It was a premeditated, planned assassination of an innocent woman. Katrina Walsh helped her every step of the way and was up to her neck in this dreadful crime.

“A more cold-blooded plan you cannot imagine. It is chilling to realise that two women could become such determined killers.”

The court heard Williams was desperate to win Mr Johnston back.

Mr McDermott said: “In the obsessive and jealous mind of Sarah Williams, Sadie had to go.”

8 Sadie's partner Ian Johnston was away on a skiing trip when his wife was stabbed to death Credit: News Group Newspapers Ltd

The court heard retired fireman Mr Johnston had left Williams when she became possessive and had started a new life with ­conference planner Sadie.

But, it was claimed, Williams grew to despise her rival.

Mr McDermott said: “She plotted to remove her so she could achieve her dream of life with her ideal man. It was a delusion.”

The court was told Williams and Walsh travelled to Germany to buy the cattle prod and Walsh even kept a diary of the murder plot which proved the pair had been planning it for 17 months.

We're talking of getting rid of her opponent ... She does seem like an evil bitch Katrina Walsh diary entry

8 Floral tributes lie on the wall outside the home Sadie Hartley shared with partner Ian in Helmshore, Lancashire Credit: News Group Newspapers Ltd

One extract from September 2014 said: “Sarah came round so got caught up in endless murder plots for Ian’s other half.”

In June 2015 she wrote: “We’re also talking of getting rid of her opponent. I agree it’s probably a good play. She does seem to be a totally evil bitch.”

Just weeks before Sadie’s death she came face-to-face with her alleged killer at a party at an indoor ski centre in Manchester where Williams worked.

The prosecution say it was at the December 2, 2015 party that Williams, from Chester, put the tracker on Mr Johnston’s car.

8 Police vehicles surround the home where Sadie Hartley was murdered in January this year Credit: PA:Press Association

CCTV picked up Williams’ car on Sadie’s cul-de-sac several times, including seven days before the murder when Walsh delivered the £3 bouquet.

Mr McDermott said the visit left Sadie “creeped out” and she sent a text to Mr Johnston about it. She told him: “A woman has turned up with a bunch of chrysanthemums but didn’t know who they are from? Xxx.”

When Ian responded: “Not me,” she said: “She knew my name. That’s a bit worrying.”

Sadie also emailed her concerns to a colleague.

8 Sadie's partner Ian Johnston arrives at Preston Crown Court yesterday Credit: News Group Newspapers Ltd

Although not at the murder, the prosecution say horse-riding instructor Walsh, also of Chester, was involved in the planning of the plot. She bought the knife believed to be the murder weapon and paid £430 cash for the car Williams used.

Mr McDermott said it took Williams four minutes and 40 seconds to park her car, knock on Sadie’s door, stun her and then deliver more than 40 knife strokes.

He added: “You can see this was a no-hesitation, determined and swiftly executed murder.”

Williams and Walsh deny ­murder and the case continues.

DETAILS OF 17-MONTH 'DEATH PLOT' ALL IN DIARY THE plot to kill Sadie Hartley was unravelled by cops who discovered Katrina Walsh had documented it in a diary, the court was told. The jury heard she wrote: “Had a long discussion of how to break Ian up from his sugar mummy.”

In entries described by police as “a remarkable and compelling record”, Walsh detailed how Williams had approached her ex-husband Kev as a potential hitman.

In August 2015 an entry read: “Wow, I may get to be instrumental in helping remove the awful woman!

“Was buzzing so much I needed a Southern Comfort to wind down a bit.”

When Mr Walsh rejected the plan, she wrote: “Plan B needed. I’m going to be involved now.”

The pals formed a plan to kill Sadie with a motorbike, the court heard. Walsh noted she had trained Sarah to ride and discussed using an IS flag to “mislead the investigation”.

An entry from October 2015 read: “Sarah turned up. Caught Hunted (a TV programme). Then discussed plans to off the c***.”

She wrote: “I’ll help out happily in all the prep. I said she could do with that zapper or she risks being injured herself.

“Took ages to wind down, all the excitement of plotting the perfect murder.”

Walsh also noted that Williams had put the tracker on Sadie’s car.

When arrested, Walsh said she was scared of Williams.

By LAUREN VEEVERS

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