A twisted French couple was found guilty Thursday of torturing, killing and torching their au pair, as authorities released a haunting photo of the emaciated young woman taken two days before her murder.

Sabrina Kouider, 35, and her boyfriend, Ouissem Medouni, 40, turned their 21-year-old nanny, Sophie Lionnet, into “something less than human” after becoming convinced she was in cahoots with Kouider’s ex, Agence France-Presse reported.

The wealthy couple killed her in the bath, then burned her body in the garden of their London home — as they barbequed chicken nearby to cover the stench of scorching flesh.

Kouider, a mom of two, was obsessed with her ex Mark Walton, an LA-based member of Irish band Boyzone — calling the cops on him more than 30 times, accusing him on Facebook of being a pedophile, of sexually abusing her cat, and of using black magic and a helicopter to spy on her, the court heard, The Sun reported.

She was convinced her nanny was spying on her for Walton and that they were trying to frame Medouni for rape.

The couple’s “unhealthy, myopic, all-consuming and groundless” obsession with Walton deprived them of reason and caused them to turn their nanny into “something less than human,” said prosecutor Richard Horwell, according to The Guardian.

The twisted pair tortured Lionnet — starving her to the point that she became skeletal and emaciated, according to a photo of her released by Metropolitan Police.

They also told the nanny they would never let her go home unless she admitted to working with the Irish crooner, and dunked her head under water until she made a false “confession,” which they filmed before murdering her.

The shy, innocent girl from northern France was “ripe for exploitation” by her violent employers, the prosecutors said.

Kouider, a fashion designer, hit her with an electrical cord and accused her of stealing a diamond pendant. Either she or Medouni, a former banker, broke five of Lionnet’s ribs and breastbone last September. They refused to let her out of their two-bedroom apartment for the last 12 days of her life.

When her remains were uncovered on Sept. 20, firefighters thought she was a child because she was so small and frail. The exact cause of death could not be established.

“Those monsters beat her to death,” the girl’s mother, Catherine Devallonne, tearfully said in court. “They left her hungry. They took away her dignity, and eventually, her life.”

The two are expected to be sentenced on June 26.