Lucas Markham and Kim Edwards, both 15, killed her mum Elizabeth and sister Katie. Picture: Supplied

The Sun reports that Britain’s youngest double murderers were today unmasked as Kim Edwards, 15 — the daughter and sister of the victims — and her 15-year-old boyfriend Lucas Markham.

The pair butchered dinner lady Liz Edwards, 49, and her daughter Katie, 13, stabbing them ten times in their beds.

Today a judge lifted the order banning their identification.

The pair were just 14 when they murdered their victims — before eating tea cakes and ice cream, watching the movie Twilight and having sex.

Both killers were handed 17-year minimum terms at Nottingham Crown Court by Mr Justice Haddon-Cave, who said the pair had a “toxic” relationship and had acted in a “grotesque” way.

Lucas Markham and Kim Edwards, both 15 now, killed her mum Elizabeth and sister Katie. Picture: FacebookSource:Supplied

Katie Edwards and Elizabeth Edwards. Picture: Facebook/Graham GreenSource:Supplied

The court was told Lucas, who admitted murder, used a kitchen knife to stab his girlfriend’s mum and her sister in the neck after attacking them as they slept at home in Spalding, Lincs, in April last year.

Kim, who helped to plan the “cold, calculated and callous” act, denied murder, claiming to be suffering a mental abnormality which impaired her ability to form rational judgments.

Jurors heard she was the “driver” behind a “cold and brutal” plot to kill her own mum and sister.

The defendants showed no emotion as they were sentenced to life — but family members wept.

The pair were ordered to serve a minimum term of 20 years behind bars each, but that has now been reduced to 17-and-a-half years on appeal.

It took a jury of seven men and five women two hours and 30 minutes to find her guilty of both charges by unanimous verdict.

In his closing speech prosecutor Peter Joyce QC said “brutality and contempt oozes from every pore of this girl” and she held the lives of her alleged victims as cheaply as she would “a hamster or a goldfish”.

Lucas Markham and Kim Edwards, both 15, killed her mum Elizabeth and sister Katie. Picture: FacebookSource:Supplied

He told the jury: “You know from her police interview just how determined those two children were to take two lives. You know just how callous they were, just how cold they were.

“You know how they planned it and you know in awful detail how they carried it out.

“But you also know this girl was the driver between those two.

“She told the police: ‘We made sure that we were definitely OK with it and he continuously asked me if I still wanted to go through with it and I said yes’.”

Dubbed the Twilight killers, they are the youngest ever couple to be convicted of double murder in the UK.

The court heard for how Lucas said in police interviews that his victim Liz Edwards had “scratched his face, back and bum” as he stabbed her to death.

He also told officers she stopped struggling and went limp after about three minutes.

Facebook chat between Liz Edwards and her daughter Kim. Picture: FacebookSource:Supplied

The court has since heard Kim Edwards remains on a five-minute suicide watch in custody.

The court was also told that Lucas has been telling fellow inmates about his sickening crimes at a youth offenders facility.

Prosecutor Peter Joyce QC said: “Just imagine that scene by the riverbank, the boy asking his girlfriend: ‘Do you want to go through with it? Do you really want to do this? Are you sure?’

“It would never ever of happened if she had said no. He was offering not to do it. She could have stopped him.

“She couldn’t bring herself to do it so she got him to. He showed her how she should do it, how she should hold the knife.

“[She showed] Sheer brutality and utter contempt for her victims. It oozes from every pore of that girl in that interview.

“Afterwards she said she felt ‘a bit sad’. A bit sad — as if it was a goldfish or a hamster.”

Lucas Markham carried out the killings. Picture: FacebookSource:Supplied

Kim Edwards planned the murders but couldn’t carry out the act. Picture: FacebookSource:Supplied

Dr Indranit Chakrabarti had previously told the court the girl’s adjustment disorder prevented her from forming a “rational judgment” and having the ability to plan.

Giving evidence, the child psychiatrist said: “She was thinking under the influence of a recognised medical condition.

“She was unable to make any rational judgment and could not plan, these are symptoms of the adjustment disorder.”

Mr Joyce said: “She was thinking clearly enough to unwrap from the backpack the shirt with four knives.

“When (the boy) goes into the mother’s room she sees he’s deviated from the plan because she whispers ‘take your shoes off’.

“This is a girl who is thinking about what she has planned and what she is doing.”

He told the court the teenage girl was “the one in control”.

Elizabeth Edwards and her partner Graham Green. Picture: Facebook/Graham GreenSource:Supplied

Katie Edwards. Picture: Facebook/Katie EdwardsSource:Supplied

But Dr Chakrabarti told the court that while the girl had “logical” thoughts, she was not necessarily “rational”, saying: “You are focusing on one aspect of the disorder.”

He said the young girl was “unable to cope” because of her medical condition.

Dr Chakrabarti said: “Her condition meant she was not able to comprehend because of the stress that she was under.”

The court had previously heard Kim was “excited” at the prospect of murdering Ms Edwards.

She told police “I’d felt like murdering for quite a while”.

She also said she and her boyfriend had “a grudge” against Liz and Katie.

The teenage sweethearts have also been described as being like “a time bomb waiting to go off” after they had become inseparable in the weeks before the murders.

He said the young couple had planned to have a bath afterwards to clean off “the inevitable blood after the killings”.

The court previously heard that the plan started as “a joke” that “escalated”.

Kim told police: “He was joking. Then he realised I wasn’t joking. Then he said he wasn’t joking either and it escalated from there.”

The couple were accused of hatching the plot to kill from a McDonald’s three days before the attack.

The couple have not spoken since their trial.

Elizabeth Edwards with daughters, Kim (left) and Katie (right). Picture: FacebookSource:Supplied

Kim told cops in an interview: “He constantly asked me if I wanted to go through with it and I was, like, yes and I asked him and he said yes.

“We decided on the Sunday, but I had felt like murdering for quite a while.”

Describing the killings, she said: “He gave me his backpack. I opened it slowly because I didn’t want to make too much noise.

“I took out a black T-shirt with four knives in it. There were two large knives with black handles, like average kitchen knives.

“He said are you sure you want to do this? I said yes, but then in the end I couldn’t do it so he did it.”

Churchgoing Liz told Lucas to “get off” her, jurors heard.

It was said that Lucas then suffocated his victims with their pillows while Kim listened to them “struggling and gurgling” at around midnight on April 13.

The knife that Lucas Markham used to kill Elizabeth and Katie Edwards. Picture: SuppliedSource:Supplied

Nottingham Crown Court heard how her 13-year-old daughter Katie died moments after Liz.

A jury was told Kim walked in while Lucas was on top of Ms Edwards, touched her hand and asked “is she dead?”

The 13-year-old victim mumbled the words: “I can’t..” in a “scary voice” which was “all croaky”, the court heard.

Jurors heard how the teens discussed in detail how they would target the victims’ necks.

A court hear they planned to kill themselves with pills and Kim left a suicide note which read: “F*** you, world. I want to be cremated and want our ashes scattered at our special place”.

Lucas Markham and Kim Edwards, both 15, killed her mum Elizabeth and sister Katie. Picture: FacebookSource:Supplied

Speaking outside court following the verdicts, Detective Chief Inspector Martin Holvey, of East Midlands Major Crime Unit, said: “This tragedy was distressing for all families involved, for Katie’s school friends, for Elizabeth’s colleagues, friends and children at the school where she worked, as well as having a shocking impact on the wider community of Spalding.

“What makes this case even more shocking is that these two were 14 years of age when they planned and committed these callous, senseless and unprovoked attacks on Elizabeth and Katie.

“This case has left a number of lives in ruins, not only Elizabeth and Katie’s family, but also the two juveniles who committed these horrendous crimes.”

Katie’s dad, Peter Edwards, 43, has since bought the plot next to her grave, saying: “I cannot wait to lay in it.”

Peter Edwards is grieving the death of daughter Katie Edwards. Picture: SuppliedSource:Supplied

This article originally appeared in The Sun