Mona Blades’ disappearance and police reliance on an orange Datsun still haunt New Zealanders 50 years on. Would such a mystery have a different outcome today? By Greg Bruce
On the Saturday morning of Queen’s Birthday weekend, May 31, 1975, Mona Blades stepped out of her brother-in-law’s car on the outskirts of Hamilton and into the staccato stop-motion nightmare of what remained of her life.
From that moment, she appears to us only in flashes. Even at the time, the flashes were few and far from hot and bright. Today, the lasting image we have of her is in black and white, but her last moments happened in colour. She wore a fawn jumper, a green rugby jersey with a white collar, a black duffle coat and brown shoes with yellow laces. She carried a brown pack and an old brown shoulder bag. Most importantly, and most memorably, she was last seen getting into an orange Datsun.
Ever since, her disappearance has been inextricably tied to that car. Even today, a google search brings up images of her alongside it. The government’s New Zealand history page on the case mentions the orange Datsun. So does the case’s Wikipedia page.

In the months following the 18-year-old’s disappearance, the search for the orange Datsun was all-consuming. Thousands of hours of police time were spent finding and interviewing the country’s more than 500 orange Datsun owners and scouring the entire 145km length of the Napier-Taupō Rd on which they believed the car had travelled.
The primacy of the orange Datsun was based on the testimony of a truck driver who said he first saw Blades running towards the car and later saw her in it. Fifty years later, police believe he was wrong.
In 2018, retired Detective Inspector Ron Cooper was one of four high profile detectives invited to take part in a review of the Blades case for the first episode of a new television documentary series called Cold Case.
As Cooper read through the thousands of documents in the case file, he noticed a tiny detail so small as to appear almost insignificant –and so small the case’s original investigators had overlooked it. But with the benefit of more than 40 years’ hindsight, it seemed clear to Cooper that it was crucial. He believed the failure to pick up on it meant the investigation took a wrong turn and generated more and more momentum, sending first investigators, then the entire country in completely the wrong direction.
The detail was this: on the day of her disappearance, Blades’ hair was short and spiky. It was so short that two trainee teachers who picked her up that day believed they were picking up a boy. But in the photos of Blades that were used by police and by the media, her hair was long and thick.

In other words, the police were asking the public for sightings of someone they couldn’t possibly have seen.
And that brings us to the problem with the orange Datsun. The truck driver who told police he had seen Blades in the orange Datsun also told police the woman had shoulder-length hair. He could have been right about one of those things, but he couldn’t have been right about both.
That alone should have been enough for police to question his testimony. But it was far from the only problem with his account. According to the detectives in the documentary, he was interviewed four times. At the first interview, he told detectives he wasn’t able to say whether the woman he saw was Blades. Later, he said it was possible it was her, but he couldn’t say for sure, because, as the orange Datsun overtook his truck on the highway, he could see her face only in profile. Finally, he said he was sure it was her, because as the car overtook him, she looked up from the passenger seat and gave him a “half-pie smile”.
“You don’t want to speak ill of the people who were running [the investigation],” Cooper says now, “but masses of information come in on those things, and sometimes you get a bit left hand and right hand.”
And so it was that while the police combed the country for an orange Datsun that now appears to be a red herring, someone, somewhere was getting away with murder.

Tracked by tech
British tourist Grace Millane disappeared from the Auckland backpackers’ hostel where she was staying in December 2018. Police were quickly able to accumulate so much CCTV footage of her last night alive they could have turned it into a movie. An improbably large proportion of her final hours played out on video, captured by cameras across Auckland’s CBD: her first meeting with her eventual murderer, their first kiss, him rifling through her handbag while she was in the toilet of a bar they visited, and the gut-wrenching last image of her alive as she walked out of the lift and towards his apartment.
After her death, the cameras continued to accumulate evidence: the killer was seen buying a suitcase from The Warehouse, taking it back to his room and taking it back out again with what police would later learn was Millane’s body inside.
Then there was the digital evidence. At 1.29am, he searched the web for “Waitākere Ranges”, then “hotest fire” [sic]. At 1.41am, he looked at a pornography website, then took intimate close-up photographs of Millane’s body. Then he accessed more porn.
He searched the web for “rigor mortis”, “duffel bags with wheels”, “flesh-eating birds” and “are there vultures in New Zealand”. He searched for industrial-strength carpet cleaners, car hire and beaches close to Auckland.
Later that morning, his cellphone pinged towers in the Waitākere Ranges, where Millane’s body was eventually found. Although he had attempted to clean his apartment’s carpet of her blood, police were still able to extract her DNA from the underlay.

Jesse Kempson was arrested within a week. He attempted to lie about what had happened, but the evidence was overwhelming. A jury found him guilty and he was sentenced to life in prison.
Scott Beard was the lead detective on the case. He says assembling a case like that one is a jigsaw puzzle. You might have an overwhelming quantity of evidence, but you still need to put it together in a way that will convince a jury.
And in spite of all the new and rapidly advancing technology, a big part of that puzzle, he says, is still made up of what people tell you. At the murder trial, key witnesses formed a big part of the case, helping to build a picture of Milane’s killer that was completely at odds with the picture he tried to paint of himself as an accidental killer.

Cormack case
The use of modern technology to build the almost seamless narrative of the murder of Grace Millane could hardly have been more different from the erratic and unreliable stitching together of disparate witness accounts in the attempt to reconstruct the final hours of the life of Mona Blades. The growth in the quantity and potency of resources available to investigators in missing persons cases during the half century between those two murders has been enormous, and steady, but if one had to pinpoint a moment in time when the evidential balance of power swung decisively towards the police, it came in the wake of the murder of 6-year-old Teresa Cormack.
When Teresa went missing on her way to school in Napier in 1987, her disappearance gripped the country. When she was found on a nearby beach eight days later, having been sexually abused and strangled to death, police began one of the biggest manhunts in New Zealand history. Despite interviewing more than 900 suspects, there was frustratingly little useful evidence and few clear leads.
Six months before Teresa’s killing, police in the United Kingdom had become the first in the world to try a new forensic technique known as genetic fingerprinting – a technique that had been accidentally discovered in a British genetics lab two years before. The technique used samples of DNA to create a unique pattern, which, like a fingerprint, could belong to only one person. In August 1987, two months after Cormack’s murder, UK police made their first-ever arrest using genetic fingerprinting.
Ron Cooper was the lead detective on the Cormack case and when he read about the case then unfolding in the UK, he immediately recognised its potential to transform investigations like the one he was working on. He had DNA samples from the Cormack crime scene sent to Britain for analysis, but after five months of trying, they were unable to get a match. The technique, he says, was not yet sufficiently advanced to create a profile from such a small sample.
But Cooper had a hunch that some day it might be, so he arranged to hold back some of the DNA found at the scene as a potential sample that could be tested if and when it was. “I remember talking to a group of detectives on a detective course about that and I said, ‘Now my name’s on the list of DIs who haven’t solved a homicide. But write it in pencil, because the science will get better.’”
In the first week after Teresa Cormack’s murder, police had picked up and questioned a man named Jules Mikus, who lived nearby and had a history of sexual offences against girls. But he also had what was then considered to be a strong alibi. He was also a skinny Pākehā, and therefore unlike the identikit sketch all the investigators had in the front of their notebooks of the heavyset Māori man who, witnesses told them, had been seen walking with a young girl around the time of Teresa’s disappearance.
In 2001, 14 years after Cormack’s murder, Cooper’s hunch paid off. The DNA sample from the crime scene had yielded a genetic fingerprint. It was compared against samples given by 845 suspects: four were of insufficient quality. Of the remaining 841, 840 were eliminated as suspects. The only one remaining was Jules Mikus. He was ultimately found guilty of Teresa’s abduction, rape and murder. He died in Rimutaka Prison in December 2019.

Interview techniques
When Blades disappeared in 1975, there was no DNA testing, no CCTV and no central police computer. The work of putting together a case was hard and manual, and it relied heavily on witness accounts. The problem with witness accounts is that they rely on memory – and memory is fragile.
Police have a better understanding of that now and have developed interviewing techniques to maximise their chances of getting accurate recall.
Cooper tells a story about a witness he spoke to while working on the Peter Plumley Walker case in 1989. Plumley Walker’s body was found in the Waikato River after his accidental death during a bondage session; two people were initially found guilty of murder but later acquitted. The witness said they had spoken to Plumley Walker outside an ASB branch in Auckland. They said they remembered the date because they had a dentist appointment that day. They also said they knew Plumley Walker personally. On the day they said they had spoken to him, Plumley Walker had been dead five days.
“That’s really common,” Cooper says, “and a lot of that is to do with how we interview people.”
He says the growing quantity of research into human memory and the growing awareness of its frailty has completely changed the way police conduct witness interviews since he joined the force. More recent police training likens witness memories to a fresh fall of snow. The key to good interviewing is to avoid trampling that snow.
“This technique is really simple. It basically lets them speak out their recall for however long it takes, without you interrupting at all. Then you go back, and you try to tease out more information from the points that seem important.”
In other words, he says, rather than asking questions like, “Did you go to the bank that day?” and “Did that person have a moustache?”, the interviewer should simply say, “Tell me what you did that day,” then sit back and let the witness talk until they’re finished. Only then should the interviewer go back and ask about specifics. “It’s a whole different way of asking questions.”
We now know from research that when you interrupt somebody, you affect the memory.
It’s not what the police did in the case of Mona Blades. During the 2018 Cold Case documentary when Cooper and other detectives revisited the mystery, they were at pains to make clear their revisionist view wasn’t intended as a slight on the detectives working on the case (one of whom, Stewart Guy, was also part of the team assembled for the documentary). They stressed that detectives in 1975 were simply following best practice for police interviews at the time. It’s just that best practice is always getting better.
“You’ll remember we were trained to get detail,” Cooper said to Guy at one point. “We used to interrupt a lot. [A witness would say] ‘I was in a car.’ We’d stop them. ‘What car? Where were you going? What direction?’ We now know from research that when you interrupt somebody, you affect the memory.”
While police were spending huge amounts of time and police resources chasing down more than 500 owners of orange Datsuns and using interview techniques that contained such memory-affecting questions, they were spending far less attention following up on cars other witnesses saw Blades getting into that day.
For instance, one person who knew her personally said they saw her getting into a darkish blue/green station wagon in Taupō. Another person, to whom she introduced herself as Mona Blades, saw her getting into a red Toyota station wagon, also in Taupō.
Today, the police webpage about the disappearance mentions both those cars. Not mentioned: an orange Datsun.
Gang connection raised
Who did it? In the documentary, and on the police website, the possibility of the involvement of bike gangs is mentioned. The documentary has actors playing bikers looking rough and bad and generally likely to commit a crime. It makes for good TV.
According to police, Blades was “friends” with some gang members and members of that gang are believed to have been passing through Taupō on the day she disappeared. In the documentary, police asked for anyone who knew anything about such a link to come forward. Seven years on, if it has led to anything, they aren’t saying.
The Listener asked the detective now in charge of the case, Ryan Yardley, about this and other questions. Through a spokesperson, he replied, “Unfortunately as this point, there’s nothing new to follow up. There are many unanswered questions regarding Mona’s movements and sightings that may never be answered as we get to the 50-year anniversary, and memories fade.”
Dave “Chook” Henwood helped found the police criminal profiling unit and has been responsible for the capture of some of the country’s worst criminals, including Malcolm Rewa and Joseph Thompson. In the early 2000s, he opened the file from an unsolved case from the late 1970s.
The victim had been abducted, assaulted and left for dead in a ditch. If that crime happened today, he says, the forensic evidence would fill a book. The case file contained precisely one page of forensic evidence, “and three-quarters of that was the credentials of the author”.
If the Blades case happened today, he says, it would be solved in a week. “There was no DNA, there were no mobile phones, there was no CCTV. Forensic evidence was negligible … It was a shot in the dark back then.”
Scott Beard says CCTV would likely play a big part in such an investigation today. Even on rural roads, such as those on which Blades was hitchhiking, the possibility of a car evading CCTV today is slim. Cameras are everywhere: on buses, trucks and even in many modern cars.
In 1975, without CCTV, DNA, cellphone records, electronic transaction trails or cell tower data, all the police had were their questions – and thousands of pages of largely unsatisfactory answers.
The only real hope of finding out what happened to Blades lies in the rapidly diminishing possibility that someone who knows what happened will speak up. True crime author Scott Bainbridge, who included a chapter about the Blades case in his 2018 book The Missing Files, says, “It’s going to take a death bed confession, I believe.”
Detective Senior Sergeant Jaedoo Danny Kim is in charge of cold cases for the police national criminal investigations group. “Police never close cases,” he says. “Each investigation remains open pending further lines of inquiry until the case is resolved. Police will never give up, and we are committed to solving these cases to provide answers to the families of their loved ones.”
Counter theory
The centre of the documentary on Blades – and its most startling moment – is the following exchange between detectives Ron Cooper, John Hope and Mark Loper (who was in charge of the case).
Cooper: “The whole thing was predicated on that she was the victim of a hitchhiker murder, but it may be that … she met her fate in a whole different situation.”
Hope: “It’s very possible it’s someone she actually knew.”
Loper: “I don’t believe Mona Blades left Taupō alive.”
Of the truck driver’s account of seeing Blades in the orange Datsun, Cooper now says, “I don’t think they should have considered his evidence at all, because of the hair thing. It was there on three documents.”
To be fair, he says, there were thousands of documents on the file. “But it was there. And it should have been picked up.”
You can feel that comment land like a punch to the gut of all those police who spent all those hours scouring the Napier-Taupō Rd in the middle of winter. And to those who spent all that time tracking down and questioning 500 orange Datsun owners all over the country. And, most importantly, to all the family and loved ones of Mona Blades.