Tulay Goren, 15, disappeared in January 1999
The father of an alleged "honour killing" victim threatened to kill her the day before she disappeared, the girl's sister has told a court.
Tulay Goren, 15, went missing in Woodford Green, north London, in 1999.
Her sister, Nuray Guler, said their father Mehmet Goren threatened to kill Tulay and tried to "beat her up" but he was prevented by other family members.
Mrs Guler also told the Old Bailey that Mr Goren had made her own life "hell". Mr Goren, 49, denies murdering Tulay.
The court heard Tulay's family disapproved of a relationship she was having with factory worker Halil Unal, due to religious differences and the fact he was 15 years older than her.
Mrs Guler, 28, also told the court Mr Goren previously disapproved of her own relationship with her husband.
Mr Goren had reacted "violently" when he discovered Mrs Guler was in a relationship and he allegedly tried to kill himself, she told the court.
Speaking through a Turkish interpreter, Mrs Guler described Tulay as a "child looking for happiness".
"She was very young and she was vulnerable," Mrs Guler said. "Maybe what she was looking for was a father. Maybe she found a love that she did not get from her father."
Mrs Guler said her father had phoned her in December 1998, when he told her Tulay had been meeting a man, and insulted her with "unspeakable words".
"He was calling her a whore," Mrs Guler said. "He was saying to me, 'I am going to grab a knife and go to the factory and kill the man'."
Tulay had run away to be with Mr Unal in January 1999 but was brought back to the family home in Woodford Green, the day before she disappeared.
Mrs Guler, who was at the house with other relatives on the night of Tulay's return, said: "[Tulay] was saying that whatever happened she would go back [to Halil's house].
"At some time she was about to jump off the toilet window but she was prevented. They intervened."
Mrs Guler added: "My father was very upset and he got cross with her and he was saying that he was going to kill her and he was prevented.
"He tried to beat her up in a rage but was prevented."
Mrs Guler said she was asked to make a coffee for Tulay and her father put some sleeping tablets in it, allegedly saying: "She should go to sleep so she doesn't run away."
Mrs Guler said she later overheard her father speaking on the phone.
"He was saying something like, 'Don't worry, I won't allow her to shout'.
"I didn't listen to him specifically but I heard this. At the time I did not think that this sort of thing could happen, I didn't believe that."
Mr Goren and Tulay's uncles Cuma Goren, 42, from Walthamstow, east London, and Ali Goren, 55, from Walthamstow, deny murdering Tulay.
Mehmet Goren and his brothers also deny conspiring to murder Mr Unal between May 1998 and February 1999.
The trial continues.