Caroline Byrne's father told a police psychologist her high school sweetheart became aggressive and stalked her after they broke up, a jury has been told.
Ms Byrne's body was found at the base of The Gap, a notorious Sydney suicide spot in June 1995.
The late model's boyfriend, Gordon Wood, 45, is standing trial in the NSW Supreme Court for the 24-year-old's murder.
Police psychiatrist Neil Schultz told the jury today he interviewed Ms Byrne's father Tony Byrne during investigations in 1996.
Dr Schultz said Mr Byrne had told him his daughter had had two long-term boyfriends, Wood and "a boy from school".
Caroline and the high-school boyfriend had been together for eight years, Dr Schultz said, and had separated in 1993 when he joined the police force, because Caroline "needed a break".
"Mr Byrne told me that the young man became aggressive," he said.
"He stalked and rang her.
"Whenever he knew where she was, he would ring and make funny phone calls."
Dr Schultz said Mr Byrne had told him the behaviour "eventually died down" and his daughter had begun a relationship with Wood.
Witnesses have told the court Ms Byrne was seen arguing with Andrew Blanchette, a police officer and her high-school sweetheart, in the months before her death.
On the night of her disappearance, Mr Blanchette has admitted under oath that he was in Rose Bay, one suburb away from The Gap in Sydney's east.
One of the key investigating officers in the case, Detective Sargeant Paul Quigg, told the jury there was "no record" of Mr Blanchette ever stalking Ms Byrne.
His whereabouts on the night of Ms Byrne's death had only become an issue in recent weeks and Det Sgt Quigg said Mr Blanchette had made a fresh statement indicating he was at a gym that evening.
Police were investigating an allegation from Mr Blanchette's ex-girlfriend that he had attempted to contact her ahead of her evidence, he said.
The woman, who cannot be named for legal reasons, says Mr Blanchette was at her home in Rose Bay that night.
Det Sgt Quigg said there were "no criminal charges to my knowledge being made against Andrew Blanchette".
He agreed with Wood's barrister, Winston Terracini SC, that he had played football with Mr Blanchette, who was medically discharged from the police force in 2000.
But Det Sgt Quigg denied playing with Mr Blanchette during 1995 or 1996, when a statement was taken from him in relation to Ms Byrne's death.
While he considered Mr Blanchette a mate, the detective said, he had no other social contact with him.
The trial is continuing.
