A Chester woman has told a court she did not murder a love rival in an 'orgy of violence'.

Sarah Williams, 35, is on trial for the killing of businesswoman Sadie Hartley, 60, who the prosecution allege she killed after former boyfriend Ian Johnston dumped her.

Miss Williams, wearing a dark business suit over a white top, sipped water as she gave evidence in the witness box, watched closely by Ms Hartley’s two children, Charlotte, 22, and Harry, 23, who were sitting in the public gallery of Preston Crown Court.

Miss Williams is accused of plotting for 17 months to kill Ms Hartley with co-accused Katrina Walsh, 56, after becoming 'obsessed' with ex-fireman Mr Johnston, 57, who was in a relationship with the victim.

The prosecution allege that Miss Williams, who at the time was a 'kept woman' with a wealthy 'sugar daddy' boyfriend twice her age, turned up at the £500,000 home Mr Johnston shared with Ms Hartley in the village of Helmshore, Lancashire, while Mr Johnston was abroad skiing.

When Ms Hartley answered the door, Miss Williams allegedly attacked her with 'demonic savagery', using a 500,000-volt stun gun to paralyse her before stabbing her 40 times.

The defendant and Mrs Walsh, both from Chester, deny murdering Ms Hartley on January 14.

Gordon Cole QC, defending Miss Williams, warned the defendant she would be in the witness box 'for some time' as he began questioning her on Wednesday.

Addressing Miss Williams, Mr Cole said: “Have you ever given evidence in court before? Have you ever been in trouble before? Have you ever been convicted of a criminal offence before?”

The defendant replied 'no' to each question.

The lawyer then asked: “Did you kill Sadie Hartley?”

Miss Williams replied: “No.”

Miss Williams said she and Mr Johnston first came into contact while skiing at the Chill Factore in 2011, but they only had the odd chat on the slopes at the time. But in 2013 they began 'liking' each other’s photos on Facebook and began to exchange messages, first having sex in September 2013 at his house.

Mr Cole asked: “Were you aware of him being in a relationship with Sadie Hartley?”

Miss Williams replied: “Yes. He told me about it.”

“Did you fall for him?” Mr Cole asked.

“Yes,” replied Miss Williams.

Ms Hartley then went on a three-month trip to Ecuador with Mr Johnston.

Miss Williams continued: “He referred quite a lot to the cost of it. He told me it was Sadie paying for it. He talked about the financial disparity between them.

"He mentioned on a number of occasions he was concerned about whether he was going down the wrong road in his life and going in the wrong direction by continuing to have a relationship with her.”

Sexually explicit messages were exchanged between them while he was away on the trip with Ms Hartley, and the day after he arrived back they had sex.

Later the pair, accompanied by their partners, Ms Hartley and Mr Hardwick, went on a skiing holiday to France together in December 2013. Neither of the other partners were aware of what was going on.

Miss Williams and Mr Hardwick then went on a three-month skiing holiday to Whistler in Canada but she agreed 'at times' she hoped her future would be with Mr Johnston.

Proceeding.