The French police officer was having lunch with colleagues based in Versailles when the call came. Two small boys had found a body in a sleeping bag.

Nicol was 25 and had been in the homicide brigade only six months. This was not her first murder case but it would become her passion. She saw that the victim, so badly beaten that her face was unrecognisable, was a young woman, like herself. O'Keefe, a 28-year-old from Melbourne, was the woman in the sleeping bag.

Nicol would learn other things that fuelled her determination to find the killer: O'Keefe was ''une innocente'', a nice Australian girl who had somehow been caught in one of the hostile ghettos of Paris, where her body had been dumped.

''There are different categories of crime,'' Nicol tells The Sun-Herald through an interpreter. ''There are gangs who do revenge killings; there are drug killings; there is alcohol and violence. But Jeanette was a completely innocent victim. She was the true victim, the poor girl who this never should have happened to.''

Her whole squad, she says, was touched by the case they came to call ''L'affaire O'Keefe''.

These two women lived half a world away from each other but had in common things other than youth. Nicol is small and slight, with piercing green eyes that blaze when she talks about the case, her words rapping out like machinegun fire. O'Keefe was also small, ''five foot nothing'', say her siblings, and she too was a pretty, green-eyed brunette.

There is another factor that led to the two women's paths crossing: chance. Many small mishaps that piled one upon the other seem to have led the normally cautious O'Keefe into mortal danger on New Year's Eve in 2001.

Eight years later, one small mishap followed by routine police procedure saw her killer caught.

On Friday, a court in Versailles sentenced that man, Adriano Araujo da Silva, to 30 years in jail, with a minimum of 20 years without parole. Da Silva, 37, a Brazilian-born petty criminal, initially confessed but later denied it. He pleaded not guilty and has said he will appeal.

He told the court O'Keefe, whom he met for only one night, was the love of his life, the woman he saw as the future mother of his children.

Police told a different story. They alleged he had bashed her around the head 13 times with an iron bar. When she regained consciousness, he strangled her with his hands. When that did not work, he strangled her a second time with an electric cord. Then he threw her body out of a window before dragging it clear of his apartment block.

Jeanette O'Keefe was the eldest of four children. She was a reserved woman, careful about whom she let into her private circle, ''not a person who went to nightclubs'', according to sister Denise. She was musical, writing ballads as a hobby and playing guitar, piano and violin.

She was savvy about work, says brother Craig. ''She went to work for PricewaterhouseCoopers and only earned $25,000 but they put her through a $10,000 course in Oracle [a computer script],'' he said. ''So then she quit and started being a consultant for $75 an hour.''

O'Keefe had been travelling alone on a European holiday when she checked out of her Paris hostel on News Year's Eve in 2000.

The hostel took bookings by the month and staying one more night would cost four weeks' accommodation. ''She didn't want to spring for a hotel,'' Denise says. She had planned to spend that night at the home of a new French friend, Elise, before catching a flight to New York.

The plan was for her to get to Elise's outer-suburban metro station where Elise would pick her up with a car because she was carrying a large rucksack.

Here came the first mishap. Elise waited at the station for an hour, but O'Keefe did not appear. Elise waited several more hours at home. She is uncertain, now, whether she might have confused the time she was due to pick up O'Keefe. Neither of the girls had mobile phones.

O'Keefe phoned another friend, a young man named Tony. She told him Elise had failed to turn up and she needed somewhere to stay. Tony made plans to meet her on the Champs-Elysees but decided to miss the meeting, he later told police. This was Jeanette's second mishap.

Denise says: ''He was annoyed at her because a few weeks earlier she had pulled out of an outing with him because she was sick. Tony later told police that [he didn't want her to stay over] because it meant he would have to sleep on the floor and he had a bad back. So he was deliberately late for the rendezvous.''

O'Keefe, by now tired and stressed, with partygoers filling the centre of Paris, then rang Elise's home and spoke to her mother. The mother gave her complex instructions in French for getting to their metro station.

Police later worked out that O'Keefe had made the call from a public phone box only 50 metres away from where Tony finally turned up to meet her on the Champs-Elysees.

Here came the third mishap: Elise's mother did not replace the phone properly in the cradle. If O'Keefe had tried to call her again that night, she would have received an engaged signal.

A small woman with a large backpack, worried about the cost of a hotel, was stranded in Paris. Here came O'Keefe's fourth and unluckiest mishap: she ran into da Silva.

Her family thinks it is possible she met da Silva on a train on the way back to Elise's home, perhaps even because she was lost on the wrong train, and accepted his help carrying her rucksack. Maybe he offered to get her to a phone, speculates Denise. ''I think she refused him [sex] and he lost it,'' she says.

The first task of Nicol's squad was to identify the body found in the sleeping bag on January 2. It was not until Interpol in Canberra sent police O'Keefe's description that Nicol had a clue.

The squad then tried to retrace her last hours. They spoke to people at the hostel and set up three lines of inquiry: kidnappers on the books; offenders who had committed crimes on trains; and about 200 single men in the apartment blocks near when O'Keefe's body was found. The men were sent orders telling them to present themselves to police, where they were asked to give a DNA sample.

Only 10 men failed to respond to the request. Da Silva was one of them.

France's full DNA database was not created until 2005-06, Nicol says, and it was another two years before technology advanced far enough to get a useful sample of the flesh that was under the fingernails of O'Keefe's right hand. She had scratched her attacker.

It was this evidence that kept hope alive for Nicol. ''I knew that one day we would get a match. DNA belongs to one person and there is no doubt and when you have a basis of evidence like that, the case becomes more compelling.''

Nicol - then five months pregnant - took the call she will never forget on February 2, 2009. The database had come up with a match.

''It was incredible,'' says Nicol, who had been emailing O'Keefe's mother, Susan, for years. With tears in her eyes, she says, ''I have goose-bumps just thinking about it.''

Nicol, by now the last remaining member of the team that had begun the investigation, shared the interrogation of da Silva. A man who lived on the edge of society, he had held a series of unsuccessful jobs including removalist and had had several brushes with the law, mostly over theft.

He had been born to a white Brazilian mother who fostered him out as a toddler before he was retrieved by his black Brazilian father, who took him to French Guyana to grow up with his step-family. He had identity issues, a hateful view of women and problems facing reality, and lacked the capacity to feel compassion or guilt, a psychologist later told the court.

He had been caught after he ran a police roadblock because he was unlicensed and uninsured. He later went to police claiming the vehicle had been stolen from him; they did not believe him and charged him, taking DNA as part of that process.

Nicol says the strategy was to keep him in the dark at first about what the police knew. ''He denied ever having met Jeanette. He said he didn't recognise her photo. He said he couldn't remember what he had been doing that night and that he never went to the Champs-Elysees.''

Told there was DNA evidence linking him to the crime, Nicol says: ''He created a story that he had found her being attacked by two black guys at a metro station and had saved her, but that she had been so hysterical that she had scratched him, too.''

Then he was told that one of his hairs had been found in the sleeping bag in which O'Keefe's body had been dumped. Realising that the weight of evidence was against him, Nicol says, he then asked to phone his girlfriend. Sitting in the police office opposite Nicol, he told his girlfriend that he had killed a woman with an iron bar - a detail not released to the public - and that he would be going to jail.

But in April, after three months in jail, da Silva recanted. In court last week he pleaded not guilty and O'Keefe's brother, Craig, and sisters, Denise and Christine, sat through a long and salacious tale in which he alleged consensual sex with O'Keefe. He claimed he threw her out when she refused more sex with him, and gave her the sleeping bag in which to sleep.

Earlier in the trial, the judge warned da Silva that his refusal to take responsibility would weigh against him. It did: 30 years is France's maximum sentence.

Nicol could not make it for the verdict. She was needed at work. But she arrived later to congratulate the family and friends.

They wanted a private photo to commemorate the moment and gathered under an archway in the court complex with uncertain expressions. What is the etiquette for this kind of snapshot? At the end of the line stood Nicol, shoulders back, wearing the tiniest of smiles, and with unshed tears in those fierce, green eyes.