How a teenager's killer was brought to justice after 34 years
A man has been convicted of the rape and murder of a teenager who was attacked in her own home. BBC News looks at how James Warnock was finally brought to justice for the horrific killing of Yiannoulla Yianni.
When 17-year-old Yiannoulla was brutally raped and murdered, she was preparing a leg of lamb for her family's evening meal.
It was August 1982, and she had been at her Greek Cypriot parents' shoe-repair shop in Hampstead, north London, before she headed home to start cooking.
Yiannoulla's mother, Elli, said she would join her soon - their home in Belsize Road was less than five minutes' walk away.
The teenager was awaiting her exam results with a view to starting a beautician's course - she used to spend time styling her hair and sitting under a noisy hooded hairdryer at home, to the annoyance of her father.
Known to her family as Lucy, after the actress Lucille Ball for her bubbly personality, she was listening to her favourite record, Forget Me Nots by Patrice Rushen, when there was a knock at the door.
She peered out of the window and whatever the man outside said, it convinced her to come down and open the door.
A young man was seen chatting to Yiannoulla on her doorstep. Twenty minutes later, a neighbour heard a scream.
Her parents arrived home half an hour later to "a sight beyond their worst imagining" - Yiannoulla's dead body lying on their bed.
She was naked from the waist down with her skirt pushed up and her chest was exposed where her top had been roughly cut open.
A post-mortem examination revealed she had suffocated, most likely as a result of her neck being held in an arm-lock. She had also been raped, bitten and punched.
Police believe the killer forced his way inside the house and chased her up the stairs. He may have grabbed her ankle as she fled - a broken chain was found on the carpet.
It is believed Yiannoulla tried to hide in her brothers' bedroom which was the only room in the house to have a lock on the door.
There was a footprint on the bottom of the door and it had been forced at its hinges.
More pieces of Yiannoulla's jewellery were found upstairs - a bangle and a broken ring - as she struggled and ran from room to room.
Police believe the attacker finally cornered her in the bathroom - when she was found her hair and clothes were soaking wet.
A police investigation began. A reconstruction was shown on TV, featuring her sister Maria, then aged 20, as Yiannoulla, but no plausible suspects were identified.
To try to keep the investigation going, her heartbroken father, George, appealed to then prime minister Margaret Thatcher and the commissioner of Scotland Yard.
He died of a brain tumour in 1988 without seeing his daughter's killer brought to justice. He was buried next to Yiannoulla in a north London cemetery.
Inquiries revealed that up to three months before the murder, Yiannoulla, Maria and their mother were twice followed by a man close to their home.
He was described as in his early 20s, 5ft 6ins with a Mediterranean complexion and black, combed-back hair. But further appeals brought no results.
The case was routinely reviewed by detectives, and in 1999 a scientist obtained a partial DNA profile from a semen stain on a bedspread.
Thanks to advances in technology, a near-complete DNA profile was found in 2003. But when detectives ran it though the database, there were no matches.
But on 30 December last year, 56-year-old James Warnock, from Camden, north-west London, was arrested for possessing indecent images of children.
Police had no idea they had caught a killer. As a matter of routine, he provided a DNA sample that was loaded on to the database.
It was a match for the semen found on the bedspread in the Yianni family home - the chance of it belonging to someone else was estimated at one in a billion.
Det Insp Julie Willats, who became senior investigating officer on the case three years ago, was at the theatre with her mother when she received a text to say a match had been found.
"I found it very difficult to sit still through the rest of the performance after that," she said.
Warnock was arrested on 12 January.
At the time of the attack, then aged 22 Warnock was living with his wife around half-a-mile from Yiannoulla's home and had been working as a tiler in a nearby street.
In a police interview he was asked what he looked like in the 1980s and he said: "How can I put it? Er, John Travolta?"
Warnock claimed he had been having a secret relationship with Yiannoulla that became intimate, a claim rejected by the jury.
The Met's control room took calls from former officers who'd been involved in the investigation over the years, wanting to share their delight at the development and to say they'd never forgotten such a horrifying case.
Det Insp Willats said: "He came across as a bit of a Jack-the-lad, and a very confident liar. His body language was telling - he got fidgety when asked for details of his sexual relations with Yiannoulla.
"It struck me in court when a witness described the man on the doorstep as 'cocky' and I remember thinking, that's him - he thought he was irresistible like John Travolta."
During the trial, Yiannoulla's brothers, Rick and Petros, and sister Maria, were forced to listen as Warnock maintained his claim that he used to go to their home to have sex with the teenager - despite evidence she had been a virgin before the attack.
Her mother, now 86, was among those to give evidence.
A jury at the Old Bailey took just over two hours to find Warnock guilty. He admitted six charges of distributing indecent images of children in 2013 and 2015, and will be sentenced on Monday.
Yiannoulla's brother Rick said the family had been scarred for life by what happened and the "soul was ripped prematurely from us all".
"The magnitude and horror of what happened that day is indescribable. We never gave up hoping and are truly grateful to the police for finally bringing him to justice."