'Psycho' who shot love rival with a stun gun then knifed her to death given life in jail
Jilted woman plotted 'perfect murder' for 18 months before slaughtering mum with 'demonic savagery'
"Bunny boiler" Sarah Williams is beginning a minimum 30-year jail sentence after paralysing her love rival with a stun-gun before "slaughtering her like an animal".
Williams (35) shot businesswoman Sadie Hartley (60) with a 500,000-volt weapon as her unsuspecting victim answered the door on January 14.
With "demonic savagery", she used an eight-inch carving knife to stab the semi-paralysed mother-of-two through the face and neck, inflicting more than 40 stab and slash wounds, before leaving her in a pool of blood in the hallway of her £500,000 home in Helmshore, Lancashire.
Jealous Williams, described as a "psycho" and "bunny boiler", was a "kept woman" already in a relationship with a wealthy 75-year-old "sugar daddy" amid affairs with other men, but had a brief fling with former fireman Ian Johnston.
He dumped her and began a new life with Ms Hartley, but explicit photos and sex texts continued between the pair while Williams plotted the "perfect murder" for 18 months to kill her rival and win him back.
Williams made no reaction as she was convicted of murder and jailed for life, with a minimum of 30 years behind bars.
Her accomplice, horse-riding instructor, Katrina Walsh (56), who kept notes detailing the murder plot in her diary, was given life with a minimum 25-year term.
The women, both from Chester, denied murder and blamed each other during the seven-week trial at Preston Crown Court.
Passing sentence, Mr Justice Turner said the "unimaginable ferocity" of the stun gun and stabbing of "loving mother" Ms Hartley was like the "slaughtering of an animal".
He added: "Let no one believe this was a crime of passion. It was a crime of obsession, of arrogance and of barbarity, but above all a crime of pure evil."
The judge said that the "unparalleled degree" of planning was "more closely redolent of a clinical assassination than a personal killing".
He added that though Williams wielded the gun and knife, Walsh was a "willing, sympathetic and energetic confederate right from the outset".
Outside court, Ms Hartley's son, Harry (25), flanked by his sister, Charlotte (23), said they had received some justice, before adding: "It will never be enough. It will never bring our mum back... for her family and friends, this will be never-ending."
Williams first met Mr Johnston at the Chill Factore dry ski slope in Manchester in 2012. The pair exchanged phone numbers and "flirty" texts followed. She then turned up at his house wearing a short skirt, high heels and red lipstick, and the relationship became sexual.
Williams had been seeing wealthy, married oil firm owner David Hardwick (75) since she was 17, and the two enjoyed dozens of exotic holidays a year. He also put £1,280 a month in her bank account.
Text messages continued between Williams and Mr Johnston as he and Ms Hartley grew closer and eventually began living together. Williams bombarded Mr Johnston with explicit photos and texts, and he, "flattered" by the attention of a younger woman, said that in a moment of "weakness" he replied to her in kind.
Williams and Walsh travelled to Germany last December to buy the stun gun as the murder plot unfolded.
A week before the murder, the pair drove to Helmshore to deliver flowers to a surprised and disturbed Ms Hartley in a sinister dry run.
At the time, Walsh wrote in her diary, which was seized by the police following her arrest: "I have no moral qualms, just a serious 'don't let us get caught' twinge."