A couple who tortured and murdered a French nanny have been jailed for life by a court in London.
Sabrina Kouider and Ouissem Medouni, also French nationals, were sentenced to life imprisonment with a minimum of 30 years on Tuesday for the killing of 21-year-old Sophie Lionnet.
Kouider, who has two children, and her partner Medouni subjected the nanny to 12 days of “interrogations” before killing her in the bath at their home in Southfields, southwest London in September 2017.
During their trial at the Old Bailey, the court heard that Kouider, 35, had become obsessed with the idea that Ms Lionnet was helping Mark Walton, a former member of the Irish band Boyzone, sexually abuse members of their family.
Fashion designer Kouider had also tried to frame her ex-boyfriend Mr Walton for the disappearance of Ms Lionnet, from Troyes in eastern France.
Medouni, a 40-year-old former banker, was “indoctrinated” into believing Kouider’s claims about a conspiracy between Mr Walton and Ms Lionnet, the court heard.
Judge Nicholas Hilliard QC said Kouider’s allegations against the victim and Mr Walton were "complete fiction".
The couple starved and beat Ms Lionnet, who had worked for them for 18 months, filming a “confession” hours before her murder in which the emaciated victim said she had drugged Medouni so he could be sexually assaulted by Mr Walton.
Kouider, who filmed eight hours of torture on her phone, had planned to hand the recordings into police as evidence.
At the sentencing, Judge Hilliard said: "I'm sure on all the evidence you were both involved in torturing Sophie in the bath in the lead up to her death in making her think she would drown unless you gave her information you wanted which was not in her power to give because it did not exist.
"The suffering and the torture you put her through before her death was prolonged and without pity.”
Ms Lionnet’s parents Catherine Devallonne and Patrick Lionnet were in court during the sentencing.
In a statement, which was read to the court earlier, Ms Devallonne described her daughter as a "reserved young girl" and said she was hospitalised when police broke the news about her death.
"I've been living this nightmare ever since," she said.
"Those monsters beat her to death," she added. "They left her hungry. They took away her dignity and eventually her life".
Both defendants denied murdering Ms Lionnet but later admitted during the trial to disposing of her body, which was discovered three days after she died.
Firefighters were called to Kouider and Medouni’s home on September 20 having been alerted by who neighbours reported seeing smoke and a “horrible” smell coming from the property.
Medouni had tried to dispose of the body using caustic acid and had started to cook food on a barbecue in an attempt to disguise the smell.
He was arrested after one of the firefighters noticed human fingers and a nose on the fire.
Kouider’s lawyer had tried to persuade the judge that her mental disorders had driven her actions but this was rejected.
"I do not think you thought for one moment you were acting lawfully,” Judge Hilliard told Kouider.
She wrote an apology letter titled “Dear Sophie”, in which she said she had "shared many good times as well as pains” with Ms Lionnet “until things went terribly wrong".
"I am suffering every day thinking of you and what happened to you that dreadful night. I only wish I could turn the clock back," the letter read.