A mother claimed her French nanny had betrayed her for a shot at stardom in a Tom Cruise movie following her arrest for murder.
Sabrina Kouider, 35, described her 21-year-old au pair Sophie Lionnet as an "evil monster" in a police interview, a court heard.
She alleged Miss Lionnet had been recruited to spy on her by her former boyfriend Mark Walton, a founding member of boy band Boyzone, in exchange for £18,000 and the promise of "fame".
The fashion designer had been taken into custody in September last year after Miss Lionnet's charred remains were found in her garden in Wimbledon, south west London.
She told police: "She told me she has been recruited by my ex Mark Walton.
"He gave her money. He used to come in the house. She was opening the garden door for him."
During a meeting in toilets at a shopping centre, he asked her to bring him documents about her employer's company, fashion and music, to find out everything about her, she said.
Kouider said: "Sometimes he used to ask her to open the door, give her some stuff to drug us.
"She told me he took my arm and did some injection on me and started touching me and he did things to me."
Asked what her reaction was, she said: "I was shocked. I could not believe.
"I was like 'you played this game. You being such an innocent girl. You are not innocent. You are bad. You are evil. You are a monster.
"'You did this because of money?' He said 'I'm going to make you a star? You going to do a movie with Tom Cruise?'
"That's for fame? I was really surprised. I was really shocked."
The court has previously heard Kouider's claims against Mr Walton and "shy" Miss Lionnet were outlandish and wholly true.
She said she met her partner Ouissem Medouni, 40, at a French funfair when she was 18 and they had an on-off relationship.
She claimed Miss Lionnet had run away a few days earlier and her partner had wanted to have a barbecue.
Jurors watched extracts of Kouider's interviews and transcripts were presented in the Old Bailey trial by Detective Sergeant Rob Tickle.
The couple have admitted perverting the course of justice but deny Miss Lionnet's murder.