Sabrina Kouider and Ouissem Medouni had accused Sophie Lionnet of being in league with Mark Walton

A couple, who killed their timid French nanny and threw her body on a bonfire because of their warped fantasy about an ex-Boyzone pop star, have been convicted of murder.

Sabrina Kouider, 35, and Ouissem Medouni , 40, beat, starved and tortured au pair Sophie Lionnet, 21, after falsely accusing her of being in league with music mogul Mark Walton, who was Kouider’s ex-boyfriend.

The couple killed her in the bath then burned her body in their garden near Wimbledon, south west London, as they barbecued chicken nearby. When neighbours alerted fire fighters, Medouni tried to pass off the charred remains as a sheep.

Kouider collapsed in tears and Medouni hung his head as the jury foreman returned guilty verdicts to murder for both. They each blamed the other for Lionnet’s death.

The two-month Old Bailey trial, which was described as stranger than fiction, heard how fashion designer Kouider was fixated with Walton and believed Lionnet was colluding with him to drug and molest the family.

The couple’s “unhealthy, myopic, all-consuming and groundless” obsession with with the former boy band singer, had deprived them of reason and turned their nanny into “something less than human” prosecutor Richard Horwell QC, had told jurors.

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They tortured her by dunking her head under water into making an untrue “confession” which they filmed before killing her.

Lionnet’s mother, Catherine Devallonne, wept as judge Nicholas Hilliard QC said claims the couple made against Lionnet had “no truth whatsoever”. The jury heard she had never even met Walton, who left the UK in 2015.

But Kouider, a mother of two, was convinced her ex-boyfriend was colluding with her nanny and swept Medouni up into the fantasy.

She had waged a five year war on Dublin-born Walton following their split, reporting him to police more than 30 times, with outlandish claims of black magic and sexual abuse of a cat, falsely accusing him on Facebook of being a paedophile, and claiming he had hired a helicopter to spy on her.



Walton had shouldered the ludicrous slurs and responded with “integrity and honesty”, the prosecution said, willingly travelling from LA to give evidence.



The murder bore the hallmarks of a psychosis known as “folie a deux” – or a “madness of two” – which is defined as a delusion shared from one individual to another, with Kouider the driving force and Medouni the willing party.

Kouider created a fantasy world casting Walton as an evil villain who seduced Lionnet with sex and promises of Hollywood stardom. Medouni, a former banker, became an ardent believer of Kouider’s twisted reality, the jury heard.

Born in Algeria , Kouider grew up in Paris, where aged 18, she met Medouni, a fellow French Algerian five years her senior, at a fun fair. Their on-off relationship, which lasted 17 years ending in the Old Bailey dock, was dysfunctional and turbulent, and marred by Kouider’s irrational jealousy and violence.

When Kouider went to work as a nanny in London, Medouni followed, working as a financial analyst for French bank Societe Generale in London until redundancy in 2012. He had “punched above his weight” in his love for her, according to the prosecution. The balding 40-year-old, known as Sam, was weak and submissive. When she went off with other men, he waited in the wings for her to return.

Kouider was involved in pyramid selling for a telecommunications company when she met Walton in a bank in Notting Hill, London in 2011. Walton, who now lives in Los Angeles, fell head over heels in love, he told the court, but once the “love goggles” wore off, found her to be calculating, manipulative and likely to flip and go “crazy” in a moment.

After they split, she went back to Medouni.

The trial heard she had depression and borderline personality disorder. One ex-boyfriend, Anthony Francois, described her as “fickle” and a “lunatic” who would lie, manipulate and target the weak. She could lash out at complete strangers, grabbing women’s hair just for looking at her, he said .

Facebook Twitter Pinterest Sophie Lionnet. Photograph: Metropolitan Police/PA

Lionnet, 21, who was pretty, shy and an “ingenue” was “ripe for exploitation” by her violent and oppressive employers, the prosecutor said. Born in Troyes, northern France, she at first seemed “happy” in her first job, but before her death, seemed “fed up” and wanted to go back to her family in France.

She was beaten, interrogated and accused of stealing a diamond pendant. Kousider hit her with an electrical cord, and either she or Medouni broke five ribs and her breastbone as the violence escalated last September. She was in such a state, the defendants refused to allow her out of their two-bedroom flat for the last 12 days of her life.

A video made hours before her death showed her emaciated, broken and terrified. She suffered a broken jaw. The exact cause of death could not be established. The prosecution said she died in the bath following water torture involving both Kouider and Medouni, though neither admitted being responsible for her injuries.

When her curled up remains were uncovered in a bonfire, firefighters thought it was the body of a child because she was so small and frail.

She had been murdered out of “revenge and punishment” over a man whom she had never even met.

Aisling Hosein, from the Crown Prosecution Service said while “only Kouider and Medouni know exactly how they killed Sophie”, they were “both jointly involved and came up with a plan to try and destroy her body and escape responsibility for this horrendous crime”.

Lionnet’s devastated mother Catherine Devallone condemned the couple as “monsters”. “No god will ever forgive you”, she said in an emotional statement, read by a police officer to the court. “You are equally as evil as one another”.

Her father, Patrick Lionnet, said the two had not only stolen the life of his daughter “so brutally and without remorse,” but had also stolen his “sleep, my happiness, my peace of mind and my future”.

The pair are expected to be sentenced at the Old Bailey on 26 June.