May 24, 2018 1:10 PM EDT

A U.K.-based fashion designer and her boyfriend have been found guilty of murdering their 21-year-old French nanny, after firefighters discovered her burnt remains in their garden in southwest London last September.

Sabrina Kouider, 35, and Ouissem Medouni, 40, starved and tortured Sophie Lionnet for weeks before her death in 2017, sometimes recording her on a mobile phone, investigators testified. They then burned her emaciated body on a bonfire while barbecuing chicken nearby in an attempt to mask the smell. The brutality of the case has shocked Britain and played out in national headlines.

Prosecutors said the couple had applied “pressure and relentless intimidation” as they tried to make Lionnet confess to plotting against them with Kouider’s ex-boyfriend Mark Walton, a member of the Irish boy band Boyzone, the BBC reports.

Sabrina Kouider and Ouissem Medouni were found guilty of murdering Sophie Lionnet, on May 24 at London's Old Bailey court
London Metropolitan Police

Walton, who lives in Los Angeles and traveled to the U.K. to give evidence at the trial, said in a statement he had “never met Sophie ever in my life.”

During the trial the couple, who are both French nationals, turned on each other, each saying the other had killed Lionnet while they were asleep.

“We will never know the full extent of the horrors Sophie had to endure as not all the ‘interrogations’ were recorded,” said Domencia Catino, a Detective in the Homicide and Major Crimes department of London’s Metropolitan Police Force. “Even in death the torture, abuse and humiliation continued by placing her partially-clothed body into a suitcase with no regard for even a semblance of a burial, before taking the callous decision to burn her in an attempt to hide their murderous act.”

The couple will be sentenced on June 26.

Write to Ciara Nugent at

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