DNA is an extraordinary crime-solving tool, but is its use breaching our human rights? As the Law Commission examines whether we need new ways to cover rapid advances in the field, Donna Chisholm investigates.
His 24-year-old victim, the only witness to his offending, remembered little of her abduction after the Pride Parade in the Auckland suburb of Ponsonby, and the attack in the quarry 40 minutes later. Thanks to the gloves, and the epithelial (skin) cells Mitchell shed into them as he beat her, she didn’t need to.
Few recent cases speak to the power of DNA evidence more profoundly than this one: the genetic profile extracted from those cells linked Mitchell not only with the quarry attack, but also with an unsolved rape, chillingly similar in detail, from 1992. This time, a much-older and less-agile Mitchell – a work injury made even walking difficult – failed in his intent to rape and the woman escaped. In May, he was sentenced to preventive detention, effectively a limitless term, for both attacks, and will serve a minimum of 10 years’ jail. He is appealing against his convictions and sentence. If he loses, Mitchell, who has diabetes and bladder cancer, could well die in jail.
Without the DNA, the 1992 cold case would never have been solved. Mitchell was 34 when he abducted a 25-year-old West Auckland mother as she walked home near Western Springs and raped her in a factory driveway; he was sentenced on his 60th birthday. The woman said she felt police at the time didn’t believe her, but the DNA profile from the semen on her body was nonetheless stored at the Institute of Environmental Science and Research (ESR) in Mt Albert.
To get a sense of the state of DNA science then, it’s useful to know that the rape for which David Dougherty was wrongly convicted occurred the same year. Despite collecting a semen sample from the 11-year-old victim’s pyjamas that would, a decade later, conclusively identify the real rapist, the ESR could initially extract no useful profile from it. Prosecutors had used DNA evidence for the first time in New Zealand only in 1990, when 18-year-old Michael Pengelly was convicted of the murder of an elderly woman in West Auckland.
If the science itself was in its relative infancy, the laws governing DNA use were non-existent. In 1995, New Zealand became one of the first jurisdictions in the world to introduce legislation, when the Criminal Investigations (Blood Samples) Act allowed police to request a blood sample, and a judge to compel a suspect to give one. Since then, amendments have been tacked on to the law, both to keep pace with the rapid advances in the technology and appease the political appetite for a “tough on crime” approach. They have given police ever more extensive powers to take DNA from offenders and suspects.
Changes in 2003 allowed police to collect samples from cheek swabs (as opposed to blood) and for the profile to be stored on the National DNA Profile Databank, run by the ESR for the police. They also extended the list of offences for which DNA could be taken, adding burglary alongside the existing crimes involving sex and violence. A year after the National-led Government was elected in 2008, the testing regime was even more radically expanded, allowing police to take a sample from anyone they intended to charge with an imprisonable offence, without the need for a person’s consent or a court order.
The result, says Victoria University senior law lecturer and crime and justice researcher Nessa Lynch, is that New Zealand now has one of the most permissive DNA regimes in the world, but one without the protection of independent oversight. Now that the Law Commission is reviewing the legislation, all that may change.
With nearly 200,000 DNA profiles in the national databank, the pool of genetic information available to police is large, and growing – about 13,500 are added each year. A further 12,800 unidentified profiles from crime scenes are held in a separate databank, awaiting a match to an offender.
Some of the key issues to be determined in the commission’s review (see bottom) include recognition of new scientific developments, the integrity and best practice of database use, human rights, privacy, control and ownership of DNA and the recognition of Māori interests. Māori, as they are in crime statistics, are disproportionately represented in the databank: about 40% of the profiles added each year are from people who say they identify as Māori. Ethnicity is not determined from the samples themselves.
“While the databank itself is not discriminatory, it can embed or perpetuate any existing bias,” says Kate Salmond, project leader for the commission’s review. “Once you have a higher proportion of a population on a databank, that same group is more likely to be investigated in future, because you target the people who are already known.”
She says police have wide discretion over which suspects or offenders to ask for a sample. “There’s a police manual that sits behind it, but not a lot of transparency for people to challenge that.”
University of Waikato associate professor Māui Hudson, who studies Māori research ethics and the application of mātauranga Māori (knowledge) to decision-making in science, is part of the commission’s working group on the review. He says the over-representation of Māori increases the likelihood they will be caught and prosecuted. “At one level you’d feel that’s a good thing. If people have done something wrong, they should be prosecuted. But it’s also obvious there are differences in how that plays out across different groups.”
Hudson, who 10 years ago worked at ESR as a Māori development manager, offering cultural advice and support for researchers, said there were discussions at the time about the appropriateness of ethnic identification. He has also raised concerns about the possible secondary use of samples, including linking to other data sets. “People would like to think that if their data ends up in a criminal space, that it stays in that space.”
Salmond says the commission is keen to discuss whether there is a need for clearer rules governing who should or should not be asked for a sample. “At the moment, it can be anybody suspected of an imprisonable offence, but they don’t take it from everyone, and they don’t use that power fully.”
The point is, however, that they can. Lynch, co-author of a 2015 book, The Collection and Retention of DNA from Suspects in New Zealand, says the scope of offences for which DNA can be taken is “huge” – and could even include littering and opening someone else’s mail. “If you are arrested or detained in relation to that, a police officer can require you to give a sample, and use reasonable force.”
She says people she’s spoken to about the legislation are shaken when they discover the extent of the powers. “A lot of people file it under something to do with serious criminals so, of course, it’s a good idea. But when you explain that even if you’re arrested or investigated for a very minor offence, the police could actually hold you down and take your DNA … for a lot of people it puts it in a very different frame.” New Zealand’s system is “extremely permissive”, she says. “There are very few instances in any type of legislation where police can use reasonable force to obtain a part of your body, essentially.”
Salmond says police have responsibilities under the Bill of Rights Act that mean their actions must be proportionate, but she agrees that, on the face of it, the law appears to give very wide powers. One option may be to rule some offences in or out. “One of our biggest issues is that a lot is happening behind the scenes and is not spelt out in the Act. It’s not necessarily wrong, but it needs to be more transparent.”
One staggering statistic from the ESR is that about 75% of new crime-scene samples match to a DNA profile already on the databank of known offenders or suspects. It’s thought to be the highest hit rate in the world and suggests police are accurately targeting their sampling.
The police, ESR and Law Commission have no idea what percentage of people who could be asked to provide a sample are in fact requested to do so. Many are repeat offenders, for example, and there’s no need to test them twice. What we do know is that although the most serious sex and violence offenders were targeted initially, the focus of DNA collection now is increasingly on volume crime, such as burglaries and car thefts. Police estimate about 70% of the profiles from crime scenes come from volume-crime offenders.
“I don’t think it’s necessarily wrong in principle to investigate volume crimes using DNA,” says Salmond, “but there needs to be a discussion about it, because things have moved on since 1995, when the law was introduced, and even 2009, when it was [last] amended. We need a new public debate.”
A big concern is the lack of independent oversight of police and ESR practices and the databank itself. Canada and the UK have ethics committees and commissioners who produce annual reports and audits of their databanks, but we have nothing similar.
Last November, the Court of Appeal criticised police for a DNA consent form used from 2010 to 2014 that omitted a number of statutory rights, including that a suspect could withdraw consent for their DNA to be stored if they were not convicted of an offence. It meant the DNA of more than 3500 people was unlawfully taken.
Salmond says the commission has been impressed by how hard the police and ESR have worked to ensure that DNA use in crime-solving is fair and compliant with the law, including the Bill of Rights Act. “The legislation’s not working any more, because it has been amended too many times and it’s too old.”
The manager of police national forensic services, Inspector John Walker, welcomes the review, saying police pushed for it as long ago as 2010, because the legislation was complicated and unwieldy. He hopes the many consent and other processes required for different types of samples will be streamlined.
“There’s something like 65 different forms to obtain the different types of sample. There are adult suspect samples, juvenile suspect samples, compulsion samples, databank samples and various others.”
He says police would have no problem with independent oversight of the regime, but says they already take a “hands-off approach” to the database. “We believe we’re doing a very ethical job. We don’t have the database inside the police; it’s run by an independent crown research institute in the ESR. We can’t just go onto a computer and have a look inside the database.”
When people are acquitted of an offence for which the DNA was taken, he tells the ESR to remove the sample. He also prepares an annual audit to ensure the database is run in accordance with the legislation.
Walker says he has no idea how many people who could get their DNA taken are actually asked for a sample, but believes it is a minority, citing statistics from some years ago that about 70,000 fingerprints were taken annually on arrest. The issue would be how useful a profile could be in future or current crime-solving – for example, it might have no value in a fraud investigation. “I believe police use their discretion pretty well. Because it’s such a complicated process, staff will do it when they need to rather than willy-nilly. It just takes so much time and effort. It’s daunting.”
On the issue of Māori over-representation in the database, Walker says one of the goals of police is a significant reduction in Māori reoffending, and that should affect the number of samples taken.
For the Law Commission, future-proofing the law in a rapidly advancing field will be a challenge, as scientists here and abroad examine ever-broader applications of the technology. DNA can now reveal characteristics such as eye and hair colour – and even age, to within a few years.
The ESR’s senior science leader, SallyAnn Harbison, says the ESR hasn’t yet been asked for such information, but it’s been discussed. Despite the crime shows that lead people to believe minute, incriminating traces of DNA are found at every crime scene, there’s often none located, and nearly a third of cases have limited material, sometimes because of a time delay, laundering or an insufficient sample.
The ESR receives about 10 requests a year through Interpol from police overseas wanting access to the New Zealand databank. The first “hit” came this year, linking Auckland man Paul Maroroa to the cold-case shooting of Robert Sabeckis in Adelaide in 2000. Maroroa was extradited in March and is awaiting trial on a murder charge.
A month after Maroroa’s extradition came the arrest in Sacramento of so-called East Area Rapist and Golden State Killer suspect Joseph James DeAngelo, ending a 40-year manhunt for the person responsible for a suspected 12 homicides and about 50 rapes in California in the 1970s and 80s. Police loaded DNA from one of the crime scenes to genealogical website GEDmatch, which linked it to a distant relative of DeAngelo, shrinking the suspect pool from millions to one family. As police closed in on DeAngelo, they swabbed his car-door handle when he parked outside a craft store. A few days later, they sent a tissue from his rubbish bin to a crime lab and found a profile matching that from semen collected at the scene of a 1980 rape and murder.
Salmond says this sort of “covert sampling” is legal in the US, but the position here is less clear. She is concerned that the lack of clarity could undermine controls around suspect sampling, and says the issues paper will explore options for reform. Because the information US police obtained from the genealogical website was publicly available online, a search warrant wasn’t required. Police here say they’ve only ever done familial searches on official crime-enforcement databases.
In June, DNA-testing technology developed here and in Australia and marketed by the ESR was credited with helping secure a murder conviction in a Brooklyn court against a 48-year-old man who stabbed his estranged wife to death in her car. The software, STRmix, helps laboratories interpret complex profiles using mathematical modelling to calculate a likelihood ratio when comparing profiles from a crime scene to a person of interest. And last year, STRmix led investigators working on a Florida shooting triple-murder to arrest a second suspect in the case, after it was used to analyse car keys, bullets, gloves and clothing in a car stolen from one victim.
It’s little wonder Detective Senior Sergeant Kim Libby is a cheerleader for DNA as a crime-fighting tool. In 2000, as officer in charge of the scene, he helped lock up Travis Burns for the 1998 murder of 33-year-old mother Joanne McCarthy in her Whangaparaoa home. Burns’ DNA was trapped under her fingernails as she tried to fend off his hammer blows. The homicide was one of the first in which it played a pivotal role in tracking the killer.
Twenty years on, he and Detective Sergeant Nick Salter, who spearheaded the Colin Mitchell investigation in the quarry case, say DNA was “a big nail in the lid” in the latest prosecution. It was supported by other important evidence – including CCTV footage of his silver Ford Mondeo arriving and leaving the scene, and tyre tracks in the quarry that matched those from his car – but none was as compelling as the profile on the gloves left at the scene. Scientists estimated it was 800 billion times more likely to have come from Mitchell than from anyone else.
Invisible to the naked eye
For the 1992 rape, however, there was nothing at the time apart from the victim’s testimony. “The DNA evidence solved that case,” says Salter. Although it is of little use in sex crimes where the issue is consent, Libby says it can be invaluable in “whodunits”. Mitchell’s explanation for his DNA being inside the gloves was that he’d tried them on at the Warehouse, but hadn’t bought them. The jury didn’t buy it, either.
From the start, the quarry attack was a high-priority investigation for the police and the ESR. The gloves were delivered to the institute’s Mt Albert headquarters a day after the attack, on Monday, February 27. Senior scientist Jason Barr, part of a team of a dozen scientists and technicians responsible for the forensic investigation of the most serious “person on person” crimes, including rapes and murders, managed the case.
The epithelial cells inside the gloves, invisible to the naked eye, were removed with double-sided sticky tape attached to a Perspex slide and dabbed over the fabric – much like we remove lint from clothes. The tape was then transferred to a small test tube, where it was suspended in a lysis buffer solution to break open the cells, releasing the DNA.
By Thursday, forensic biologists had not only developed a full profile from the gloves, but also had a match to the 1992 rape. For Barr, a 10-year-old primary school student in 1992, it was the first match to a cold case. Suddenly, an already high-priority file was code red.
“The balloon went up at that point,” says Salter. “Have we got a serial rapist?” A familial search of the databank – used in only the most serious cases – was launched, generating a list of names of people who could be related to the offender. None of them was, but the list nonetheless provided a flukish breakthrough.
One of the names on the list was for a “Mitchell”, and by that stage, police already knew that the owner of one of the silver Ford Mondeos registered in the Auckland region belonged to Colin Jack Mitchell. When his name was loaded into the police computer on March 7, details of his conviction and imprisonment for raping a sex worker in 1984 in startlingly similar circumstances popped up on the screen. The long-time truckie, president of the Onehunga RSA, was now at the top of the suspect list. Investigators had already whittled the list of thousands of Mondeos down to 77 still of interest – Mitchell’s name would at some point have been checked against the criminal database – but the lucky break gave them a few days’ head start. Mitchell had just five days of freedom left.
At 2pm on Friday, March 10, 11 police arrived at Mitchell’s flat in Onehunga with a search warrant, seizing his toothbrush, razor and the Mondeo. Mitchell, who lived alone and has no family barring a sister, had moved in about a year before. He was a hoarder and the place was a mess, says Salter. “He wasn’t expecting visitors.”
At the ESR, Barr stayed late waiting for the exhibits. A team was rostered on over the weekend to fast-track the analysis. Somewhat surprisingly, no trace of the victim was recovered from the Mondeo, although Mitchell was sufficiently forensically aware to have cleaned it the day after the quarry attack – a task caught on CCTV cameras at his Penrose workplace. Tests were conducted on eight samples from the car, but because the victim couldn’t remember where in the Mondeo she’d been – front, back, footwell or even the boot – scientists had nowhere to focus their attention. The time delay, and Mitchell’s cleaning efforts, had likely had an impact.
Ultimately, it didn’t matter, thanks to Mitchell’s toothbrush. By midday on Sunday, March 12, Barr emailed police: they had a match. He didn’t put it that way, of course, saying instead there was “extremely strong scientific support for the DNA from the glove and the toothbrush originating from the same person”.
It’s satisfying for the scientists, says Barr, but their thoughts are always with the victims. “This isn’t a TV show; people have gone through harrowing things. We take our job incredibly seriously. Just remember that after you’ve finished watching the show or reading the story, the people involved are dealing with this for the rest of their lives.”
Within an hour of Barr’s email landing at Auckland Central police station, Mitchell was under arrest. At his trial in February, he continued to profess his innocence, but the jury didn’t believe him. For the prosecution, and the women he attacked who didn’t know his name, or couldn’t remember his face, DNA was perhaps the most powerful witness of all.
Have your say
The Law Commission is due to release an issues paper on the laws surrounding DNA use in criminal cases by September or October. It is seeking feedback on questions, including:
- In what situations, and for what kinds of offending, should the police be able to obtain DNA samples?
- How long should police be able to keep the samples and/or profiles?
- Should police be able to do familial testing (using the databank to identify family members)?
- Should the ESR be able to analyse DNA samples found at crime scenes to find the likely ethnicity or other genetic characteristics of that person?
- Should organisations other than the police be able to use information from the databanks?
This article was first published in the June 30, 2018 issue of the New Zealand Listener.