A fashion designer accused of murdering her French nanny was charming and manipulative with a violent streak, an ex-boyfriend revealed.
Frenchman Anthony Francois said Sabrina Kouider, 35, took advance of "weaker" people and got into a fight with someone "just because they looked at her".
The Parisian fork lift truck driver's statement was read out in the trial at the Old Bailey of Kouider and Ouissem Medouni, who are accused of murdering 21-year-old Sophie Lionnet.
He said: "At the time I met her she used to say she thought of me as her little brother but at the time Sabrina had a relationship with Ouissem Medouni. We used to all go out together and after a few months I started going out with Sabrina.
"Sabrina and Medouni were often arguing, then got back together. It was like cat and dog."
Mr Francois said he had a relationship with Kouider for six months.
She was strange. She could be lovable and she could be detestable. There was no explanation for this change in moods, she would often shout and become aggressive. Her behaviour was difficult, incomprehensible. She loved attention.
He went on to say Kouider would lie and was sometimes violent, and "pulled the hair of girls in the street" because of a "look".
Mr Francois said Medouni was distant, cold and "insular".
During an interview at Lewisham Police Station, he said: "She had a dual face, a dual personality. She knew who she targeted, in other words the weaker ones. She knew how to take advantage of people, but not anyone. That's my gut feeling."
He said she was "manipulative" and could "charm" and tell lies.
On her relationship with Medouni, he said: "She was certainly in love with him - he was her first man."
He claimed Medouni caused a scar on her back.
Mr Francois last saw Kouider five and a half years ago, before she went out with former Boyzone star Mark Walton, the Old Bailey heard.
She allegedly became obsessed with the idea that Mr Walton was in cahoots with Ms Lionnet to drug and abuse her family.
She and fellow "believer" Medouni, 40, tortured Miss Lionnet into a confession, killed her in the bath and threw the body into a bonfire, it is claimed.
The couple, from Wimbledon, south-west London, have admitted perverting the course of justice but deny murder.
Earlier, judge Nicholas Hilliard QC told jurors that Mr Francois had refused to come to court to give evidence, so he could not be cross-examined about it.
Giving evidence, Kouider said Medouni had slapped, kicked and pushed her during their "up and down" relationship.
She said: "He was with me for sex, nothing else, and money."
Kouider told how she was born in northern Algeria where she was "sexually abused" before moving to Paris.
When she was young, she fell from a balcony and broke her back, the court heard.
Kouider said she had various jobs - selling pancakes, working as a nanny, at Royal Mail in Chelsea and in a bank.
After meeting in 2001, she lost her virginity to Medouni.
When he told friends about it, she was "really upset" and got so drunk she ended up in hospital, jurors heard.
Medouni, known as Sam, later accused her of cheating, slapped her face and called her "dumb", the defendant said.
During an incident at his father's home, he grabbed her hair and pushed her against a door, causing pins in her back to loosen, she said.
On a later occasion, Medouni allegedly kicked her leg "very hard" and police were called.
Kouider told jurors how Medouni used her flat in Queensway "like a hotel".
She said: "It was like I don't exist for him.
"He used our flat as a hotel."
He left and Mr Francois moved in briefly, but Kouider said he got on her nerves, and Medouni returned in 2009.
In 2011, the couple split up again after a trip to Barcelona.
On the work holiday organised by her telecommunications firm, she was invited to a party attended by US President Donald Trump, jurors heard.
On the relationship breakdown, she said: "We did argue. He was always making me cry. I did not understand why his behaviour was like this with me. I was not asking for much, just to be together in the right way."