Girl, 13, stabbed mother-of-three over 140 times then left her body in burnt out property, murder trial hears
The teen allegedly conducted research before the killing and used more than one knife
A 13-year-old schoolgirl stabbed a mother-of-three over 140 times before leaving her body in a burnt-out home, a court has heard.
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The teen, who can't be named for legal reasons, is accused of murdering Marta Bednarczyk, 43, whose body was found in a burnt terraced property in Wellingborough, Northamptonshire, in March.
Lincoln Crown Court, sitting at the city's magistrate's court, heard the defendant messaged friends after the killing to tell them she "probably wouldn't be in school for a while".
She accepts unlawfully killing Ms Bednarczyk, but denies murder claiming diminished responsibility.
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Jurors heard the defendant had researched what sentences were given to a "13-year-old convicted of murder" before the killing took place.
Opening the case, prosecutor Samuel Skinner KC said the girl initially claimed a third party had attacked the victim.
The jury were told she conducted research before the killing and was seen smiling by a police officer and nurse at a hospital where she was taken to after the incident.
Mr Skinner told the court: "She also researched what the sentence would be for a 13-year-old convicted of murder.
"Whatever she might say now, we say that this killing was premeditated."
During the Crown's opening speech, it emerged that Ms Bednarczyk was pronounced dead at the scene after her body was pulled from the smoke-filled living room of the property into a hallway by fire crews.
A Home Office pathologist subsequently examined Ms Bednarczyk’s body, finding wounds to her face, neck and back, the trial was told.
Mr Skinner said: "[The defendant] used more than one knife. The pathologist examined Marta’s body and found there were at least 143 sharp force injuries – 65 were in her head and her neck.
"Seven were in the front of her torso, 33 were in her back, ten were in her arms and 18 on her hands and wrists."
One of the injuries entered the victim’s brain while two others entered her lungs.
After the jurors were given initial legal directions by the judge, Mr Skinner said the girl is claiming diminished responsibility, which would make her guilty of manslaughter rather than murder.
He told them: "In truth this issue of diminished responsibility is likely to be the main focus of your attention in this trial because we, the prosecution, do not accept that she has the benefit of the defence of diminished responsibility.
"We say that we will make you sure that this is a case of murder because she intended to do really serious harm."
The prosecutor said it was "the sad truth" that what lay behind the killing may never be known.
Mr Skinner added: "Difficult as it may be to accept, this killing is nothing to do with her mental health – as much as we all might want the comfort of saying to ourselves that mental health and diminished responsibility explains what she did.
"Why do I say this? Because of the evidence of her premeditation. I have told you about the research that she was doing and because of the evidence of her lies, and because of the evidence of respected and experienced medical professionals who say she did not have an abnormality of mental functioning."
Ms Bednarczyk was not armed with a knife, he said, and the defendant's age did not "explain or excuse murder".
Family tributes released after her death described the victim as a "very caring woman" and "a loving mother".
The defendant sat on the back row of the court benches to listen to the Crown's opening speech, accompanied by a social worker and an intermediary.
The trial continues.