Police and scientists re-investigating the rape and murder of a young girl more than 40 years ago have made a dramatic DNA discovery which they hope will finally crack the baffling cold case.
Alicia O'Reilly, 6, was found dead in her bed in the Auckland suburb of Avondale in August 1980, while her sister Juliet, 8, slept just metres away in the same room.
The horrendous crime shocked the country and hundreds of suspects were questioned in the homicide investigation, with every home and business in the neighbouring suburbs visited by police officers.
Alicia's killer was never found.
The startling new DNA discovery has ruled out the original prime suspect but reinvigorated the investigation 41 years later.
Police are confident they'll now be able to finally solve the case and are now screening hundreds of other potential suspects in search of a DNA match.
While forensic science was rudimentary in the 1980s, and the idea of matching DNA samples was akin to science fiction, detectives working on the case decades later believed that important evidence - hair and semen left by the killer - had been inexplicably destroyed during the original investigation.
Yet in a stunning twist last year, some of the crucial swabs were discovered in an unmarked envelope in the bottom of a cardboard box in police archives.
More samples were unearthed in storage rooms of the Auckland DHB pathology department; glass slides preserving samples from the post-mortem examination of Alicia in August 1980.
The long-lost evidence was tested by scientists at ESR, the Crown research institute, who were able to extract a full DNA profile for analysis.
"That was a high-five moment for us, as a team," said Detective Senior Sergeant Ngahiraka Latimer, the officer-in-charge of the investigation.
However, no DNA match has been found. This is despite the genetic code being compared to hundreds of thousands of profiles, collected from criminals or crime scenes, held in databanks in New Zealand and Australia.
DNA has been routinely collected from serious criminals since the mid-1990s. So the lack of a hit suggests that either Alicia's killer did not commit another offence, which police consider to be unlikely given the sexual nature of her death, or died before his DNA could be collected.
Another possibility is he no longer lives in New Zealand or Australia.
Despite not having immediate success with a DNA match, detectives working on the case believe they are closer than ever to identifying Alicia's killer.
This is because, prior to the discovery of the DNA profile, any person nominated as a suspect could only be eliminated from the inquiry by old-fashioned detective work to confirm their whereabouts on the night Alicia was killed.
In the 1980s, there were no digital footprints - smartphone GPS, credit card or Eftpos transactions, social media posts and security cameras - to track someone's movements.
Someone's alibi often relied solely on the word of a family member, friend or colleague and the memory of well-intentioned witnesses can be notoriously mistaken within a few days, let alone decades.
Now armed with the killer's DNA profile, a suspect can be ruled out - or the culprit identified at last - with nothing more than swabbing the inside of someone's mouth.
The police and ESR are working their way through a list of 800 suspects, with more than 140 "persons of interest" ruled out so far after giving voluntary DNA samples.
One of those eliminated was the prime suspect favoured by the original inquiry team, a 23-year-old man who lived near Alicia's home on Canal Rd. He had suffered permanent brain damage in an accident and as a result, had the mental age of an 8-year-boy.
When questioned by police in the 1980s, the young man denied any involvement but described a vivid dream in which he saw a small boy enter the house, then kill and rape Alicia.
For more than 40 years, his family carried the weight that he might have been involved in her death.
DSS Latimer says the DNA profile means the suspect has been conclusively ruled out, in news the police shared with the family in an emotional meeting.
She appealed for anyone with any information to contact the police.
"People might have thought at the time that the police had the offender, so they didn't come forward, but we don't have any suspects in mind," said Latimer.
"So we really need the public's help to share any information, however small it may be, it can still be relevant to us. The smallest piece of information can lead to the biggest breakthrough and we really want to solve this for Alicia's parents, Nancye and Barry."
Nancye O'Reilly, 68, told the Herald she was shocked when the police told her that the crime scene evidence believed to be destroyed was, in fact, discovered in storage.
Shock turned to elation, said Nancye, before she tried to keep her expectations in check.
"That's what I've had to do over the years. Not get too elated, or too upset about things," said Nancye, who now lives in Whakatane.
"But getting a full DNA profile is a major breakthrough."
While she questioned how such samples could be listed as destroyed in police records, then found decades later, Nancye believed there was a silver lining in the evidence being lost for so long.
If the samples had been tested for DNA back in the early 2000s when the science was in its infancy, Nancye says a full profile may not have been possible for ESR to obtain, or the evidence destroyed in the process.
"My philosophy in life is what will be, will be. And this wasn't meant to happen until now. You have to look at the positive side of it."
While excited by the possibility of finally learning who killed her daughter, Nancye says the discovery of the DNA profile has also "thrown her backwards".
"It's a very strange, surreal feeling of having one foot in 1980 and one foot in 2021 ... I'm waiting, waiting, waiting," says Nancye.
"Does it bring back the pain? Yes, it does. Does it bring back hope? Yes, it does."
If the police do find Alicia's killer more than 40 years on, Nancye says her need for revenge is now gone.
She's gone through the anger stage of the grieving process, and has forgiven the man who killed her daughter. For her own sake, not his.
She doesn't want a criminal trial, just a name to put to the "faceless monster" who has given her so many sleepless nights.
"When I was young, I was able to curb my emotions. Now I'm nearing 70, I find it very very hard. You just think, how many years have I got left? Can we please have an answer before I pass?"
A veteran detective on the case since the first day of the investigation has never given up trying.
As a rookie in the CIB, Stu Allsopp-Smith was on his hands and knees scouring the long grass outside the O'Reilly home for evidence in August 1980.
His police career progressed through working on countless murders and drug investigations, to the rank of detective inspector, although the disturbing death of Alicia O'Reilly remained burned into his mind.
His persistence behind the scenes led to the discovery of the killer's hair samples in 2019, thought to have been consumed by the blood-type testing process in Australia back in 1980.
In fact, not all the hairs had been tested, and unbeknown to the police, the spare samples had been returned to the ESR.
At Allsopp-Smith's urging, staff at the ESR searched its archives and found the long-lost hairs.
ESR scientists were unable to obtain a DNA profile from the hairs, but the discovery was enough to convince the police hierarchy to commit significant resources to solve the cold case.
A new team of detectives, led by DSS Latimer, was established to re-investigate the murder with a fresh set of eyes.
The first task was to rifle through the investigation file, 16 cardboard boxes, and manually scan thousands of pages of documents into a digital format which is easier to search.
Latimer grabbed the first box. At the bottom was an unmarked brown A5-sized envelope, which when Latimer opened, had two swabs inside plastic tubes marked "Alicia O'Reilly".
"That was another high-five moment," says Latimer.
The swabs were sent to the ESR laboratory in Mt Albert where scientists were able to extract a partial DNA profile. The genetic code was put through New Zealand's DNA databanks, both for convicted offenders and DNA found at crime scenes, but without a match.
The swabs had been recorded as "destroyed" in the police evidence logbook, a surprising decision which had been confirmed verbally by the officer-in-charge of the case in the 1980s.
This prompted another question - what else still exists?
While Allsopp-Smith had previously asked the pathology department at Auckland District Health Board to search their archives, without success, Latimer repeated the request.
This time, the pathologists found something. Extra swab samples had been taken during Alicia's post-mortem examination, which had been wiped onto a glass slide to transfer material, which was preserved under a glass coverslip.
ESR scientists soaked the slides, which had been fixed together, in a corrosive solution for four days to gently prise off the coverslip. This time, a full DNA profile was extracted. Again, there was no hit on the DNA database.
But ESR was also able to perform another DNA test to analyse the Y chromosome, which is passed down through the male side of the family.
If a nominated suspect is dead, or perhaps refuses to give a voluntary DNA sample, the police can approach male relatives for a reference sample to compare to the killer's profile. This could eliminate the suspect from the inquiry, or confirm a match for the police to investigate further.
Anna Lemalu is one of the forensic scientists at ESR who analysed the DNA profile of Alicia O'Reilly's killer. She then compared the results to more than 200,000 profiles held on the New Zealand databanks, as well as in excess of 100 voluntary samples.
Working on a cold case more than 40 years old was "out of the ordinary", said Lemalu, especially when ESR did not know how the samples were stored over that time.
However, she said DNA can last a "very long time" in the right environment and in this case ESR went beyond the standard tests, in order to obtain the full profile.
"This was great lab work, I'm very confident in the quality of the result," said Lemalu, despite the age of the sample.
If a suspect's DNA did match the profile of Alicia's murderer, Lemalu said that it is possible that the likelihood of finding the DNA left at the crime scene could be more than 100,000 million times greater if it had come from the suspect, rather than from another person selected at random from the general New Zealand population.
While the DNA profile has yet to hit a match, Lemalu said the police investigation now has the "best possible" result to compare to those of potential suspects. And, hopefully, solve a terrible tragedy.
"It's why we do what we do," said Lemalu. "We would love to be able to provide that information and help the police in their investigation."
The same thought drives Latimer, as it did for the now-retired Stu Allsopp-Smith before her.
"The thing that struck me most is that Alicia was home that evening, asleep in her bed. Other people were in the house, her sister Juliet was asleep in the bed next to her. Someone has entered that house and murdered and raped her," said Latimer.
"I can't even imagine, actually, what Alicia's parents went through ... they're amazing people, and I'm hopeful we can provide some resolution."
• Anyone with information for the police can call 105 and quote either Operation Sturbridge or the case file number 800816/3613.