A fashion designer and her boyfriend who tortured a French nanny were convicted of her murder today.

Sabrina Kouider, 35, and her partner Ouissem Medouni, 40, killed Sophie Lionnet, 21, then burnt her body in their back garden – which they tried to disguise by barbecuing chicken.

They had tried to get her to confess to “outlandish” claims Sophie was in league with Kouider’s ex – Boyzone founder Mark Walton – which they taped.

When the jury returned their verdict after 29 hours of deliberation, Judge Hilliard QC told Sophie’s parents: “There was no truth whatsoever in the allegations that were made against your daughter, I want you to hear that from me at the first opportunity.”

Sophie Lionnet, 21, from Paris, was working as a nanny for the couple (Image: Internet unknown)

Koudier sobbed as the verdicts were read out and tried to make a comment. But the Judge refused to hear it and ordered her to sit down.

Kouider was “fixated” with Mark and accused him of being a paedophile who was controlling the nanny using “black magic”.

She accused Sophie of working with him to abuse children and plotting to shoot dead the family, despite the fact he had never met her and lives in Los Angeles.

A total of 18 interrogation videos, lasting over eight hours, were found on a mobile phone in the six weeks before the death.

The Old Bailey heard the couple, who met in 2001, were both “drowning her in the bath” the night she died.

The nanny’s body was discovered on September 20 last year after firefighters were called to the £1million house in Southfields, south west London.

They denied murder and blamed each other for her death, both saying they had fallen asleep and woken up to find the other had killed Sophie.

But jurors rejected their claims, and Kouider and former financial analyst Medouni were both convicted of murder.

They had both previously admitted perverting the course of justice by burning the body.

Judge Nicholas Hilliard QC, the Recorder of London, adjourned sentencing for reports.

Kouider and Mark had a two-year relationship which ended around 2013, which he described as “very turbulent”.

Prosecutors said her love “soon turned to anger and bitterness”, and into a form of “obsession”.

She accused him of being a paedophile in a Facebook post under a false name in 2015 to which she accepted a caution for sending the malicious communication.

Sophie was “shy and timid” but was “controlled and manipulated” by Kouider and Medouni.

Richard Horwell QC, prosecuting, said: “The life Sophie led in Wimbledon was at times bizarre and oppressive.

“It appears for example she was hardly paid for her work but Sophie thought that was acceptable because she believed Sabrina could not afford to pay her.

“Sophie had a big heart but was not worldly wise and it was easy to take advantage of her. Kouider was seen to shout and scream at Sophie. She was threatened with imprisonment, rape and violence.”

Kouider made a series of accusations against the nanny from August 2017, including that she had stolen a diamond pendant, as a way of “intimidating and controlling” her.

The accusations grew until she alleged Sophie had let Mark into the home where he drugged the whole family and sexually abused them.

She claimed this included taking semen from Medouni after he was unconscious to frame him in a charge of sexual abuse.

Horwell said: “At the centre of this trial is the fact these inventions or beliefs concerning Mark Walton formed a central part of the reason why the defendants murdered Sophie.

“The pressure increased and so did the violence. The last days and hours of her life must have been truly wretched.

“She was subjected to brutal and oppressive inquisition and significant violence. Sophie became a prisoner in the home and must have been terrified.”

He added: “It is likely that never before will you have encountered a combination of individuals such as Sabrina Kouider and Sophie Lionnet – one being vindictive, overbearing and controlling, the other being timid, uncomplaining and especially vulnerable to manipulation and threats.

“A unique and highly dangerous combination that led to murder and the attempt of disposal of a body.”

Sophie suffered fractures to her sternum, her ribs and her jaw as well as bruising to her back and chest from the beatings.

But the full extent of her injuries and the exact cause of her death remain unknown due to her body being burnt.

The couple planned to dispose of the body and to explain her disappearance by inventing a story she had left their employment “under something of a cloud” and returned to France.

Sophie’s mother, Catherine Devallonne, was told by Kouider her daughter could not come home in two calls months before she was murdered.

Catherine Devallonne, the mother of murdered French nanny Sophie Lionnet, is comforted as she arrived at London’s Central Criminal Court today (Image: AFP)

Mark, who is now a judge on the Vietnamese version of X Factor, Vietnam Idol, told the court he had never met nor heard of Ms Lionnet.

Describing his relationship with Kouider, he said: “She shared some stories from her past and I felt that brought us closer. But it was very turbulent, it was probably the most turbulent relationship I’ve ever had.

“She would go from being softly spoken with a gentle French accent to just flip and get very angry and wouldn’t care where we were. She just went crazy over something quite trivial. She is a very intelligent woman but she has a calculating streak.”

During their relationship there were between three and four different nannies working for Kouider, who sacked them for allegedly stealing and being abusive.

Court artist sketch of Ouissem Medouni and Sabrina Kouider, who were convicted of murder (Image: PA)

Medouni said Kouider had screamed “what have I done?” and he found the lifeless body of Sophie in the bath wearing pink pyjamas under water with her eyes open.

He said he tried CPR, before putting the body in a suitcase and later burning it after Kouider suggested so.

Medouni said his partner had “destroyed” his life but he still loved her, and insisted he was not violent but didn’t do “enough” to stop Kouider killing.

Meanwhile, Kouider said Medouni made her climb in a suitcase after killing the nanny to see if Sophie would fit while he watched and laughed.

She said he warned her that Mark would come and “hurt” her if he went to prison.

She said she fell asleep, adding: “When I woke up I saw Sam next to Sophie’s body. He was trying to resuscitate her.

“He said he didn’t mean to. She was driving him crazy. He said it was an accident, he didn’t mean to.”

Medouni told the trial Kouider was friends with Duncan James from Blue, who had threatened her old landlord with a crowbar.

But in a statement, the pop star said he met Kouider once, together with Mark, in 2012, and denied ever being involved in the crow bar incident.

Kouider claimed she saw him shaking and waterboarding Sophie on September 18 last year, hours before the death.