Forensics: Crime scene misinformation

by Ruth Laugesen / 26 March, 2013
Convicted murderer Mark Lundy has won a hearing at the Privy Council, at a time when the reliability of forensic evidence is being questioned as never before.
Mark Lundy Mark Lundy, photo Mark Mitchell/NZH

Two specks of tissue found on a polo shirt and what a jury were told about them could hold the key to whether convicted killer Mark Lundy eventually walks free.

A dozen years after Lundy was convicted of killing wife Christine and seven-year-old daughter Amber, he has won a three-day hearing in June before the law lords of the Privy Council. His lawyer, David Hislop, will argue that the Crown botched key forensic evidence.

In the original trial, the Crown produced an expert from Texas who testified the specks on Lundy’s shirt were brain tissue from Christine Lundy. Part of the defence’s argument will be that the science was unproven and shouldn’t have been presented to the jury.

The case offers a glimpse of the power of forensic evidence to sway a jury. But although television programmes such as CSI: Crime Scene Investigation make forensic science appear more trustworthy than ever, in reality it is under question like never before. Some forensic procedures here are set to change as a result.

Fingerprinting, shoe prints, ballistics testing and fibre- and hair-matching are all under fire for being based on sketchy science or for being open to subjective judgment and bias. Last month, the US Government moved to clean up sloppy forensic testing by establishing a National Commission on Forensic Science to set standards across the profession, with another agency to double-check existing forensic science techniques.

Last year, the FBI launched a review of thousands of convictions involving claimed “matching” of fibre and hair samples. In 2011, a British inquiry brought fingerprinting reliability into question after it found human error and faulty processes were to blame for four fingerprint experts wrongly placing a woman at a crime scene.

And in 2009 a sweeping US National Academy of Sciences review of forensics found that of all the forensic tools available, only nuclear DNA – found in the nucleus of a cell – could conclusively link an offender to a crime scene. Fingerprint analysis is open to multiple sources of error, as are shoe prints, tyre prints and attempts to match bullets and cartridge cases to a particular weapon, says the report.


Here, dubious forensic evidence from a bloodstained sock print was one element in winning David Bain a retrial. And in the trial of Ewen Macdonald for the murder of Scott Guy, lawyer Greg King sensationally challenged forensic evidence on whether shoe prints at the scene matched a size 9 dive boot Macdonald was said to have owned. The shoe print had 32 wavy lines across the sole but the boot had only 29.

At Crown forensics agency ESR, which provides consultancy services to the police, changes are under way to how ballistics and footprints are analysed to reflect concerns about possible bias.

However, ESR head of forensics Keith Bedford says the changes are not a result of the Macdonald trial. He says he had no problem with his scientist David Neale’s evidence in that case, as Neale made it clear from the beginning it was not a clear footprint match. “It was inconclusive evidence from the get-go.”

But the changes are an attempt to eliminate possible “contextual bias” in the double-checking of expert opinions on ballistics and shoe prints. At the moment, if an ESR expert determines a bullet could have come from a particular gun, it is then referred to a second scientist for checking. But the second scientist knows there has already been a positive match; otherwise it would not have been referred. Bedford says there are plans to occasionally throw in a case where there has been no match found, to reduce the possibility of prejudice.

Similarly, with shoe-print analysis, the ESR is set to trial a new method that will give the second scientist less information about the prints being examined. It will be an anonymised “cutout”, meaning it will be shorn of any case information. “It tries to keep the assessment as clean and as free of contextual bias as possible,” says Bedford.

In the US, hair and fibre evidence that compares visual appearance has been thrown into doubt. DNA testing of hair is a separate, more reliable technique. Here, Bedford says, hair comparisons have not played much of a role. “I can’t recall a historic conviction where hair comparison was offered as a crucial piece of evidence, it’s just never featured that strongly.”

In the Scott Watson murder trial, hair samples said to be from Olivia Hope were tested for DNA, not visual appearance. However, fibre evidence has on occasion been important in a serious conviction, says Bedford, who claims that evidence would still stand up. “It’s an area of work we have looked at closely, and have assessed our approaches and our techniques over several decades.”

Ewen Macdonald Ewen Macdonald, photo Mark Mitchell/NZH


He says New Zealand is in a better position than the US because forensic testing, with the exception of fingerprinting, is done at a scientifically based agency separate from the police. In the US, forensic testing is done within the police force. “The National Academy of Sciences report was certainly a wake-up call for the standards of forensic science, particularly in the US, but none of us can afford to be complacent.”

Police forensic services head Inspector John Walker says fingerprinting procedures were reviewed here in the wake of the British fingerprinting inquiry and were found to be “reliable and rigorous”. “Fingerprint evidence can be extremely compelling and the New Zealand Police fingerprint sections have a policy of erring on the side of caution with regards to identifications to prevent the potential for miscarriages of justice.”

But, says independent forensic scientist Anna Sandiford, “New Zealand is no more perfect at presenting science in court than any other country”. She says there are not enough avenues to review the cases of those convicted on dubious forensic evidence.

“There is no process for looking back. In England and Wales there is a Criminal Cases Review Commission.” Sandiford says such a review authority needs to be set up here.

But surely those who feel wronged, as Lundy does, can pursue a legal appeal? Sandiford says that path is only open to a few, as it requires a rare combination of money, a determined defendant and a team prepared to fight to the bitter end.

“In some of these cases, it’s not the law that’s a problem; it’s the basis of the case in the first place that needs examining. We’ve had the Crewe case, the Watson case, the Bain case, the Lundy case, the Pora case. All those together should be enough to say we’ve got more than an isolated issue. Maybe there are some other cases that need an avenue for this kind of re-examination. I think there must be more cases.”

Anna Sandiford with a photograph of a bloodied footprint treated with luminol, during the retrial of David Bain. Anna Sandiford with a photograph of a bloodied footprint treated with luminol, during the retrial of David Bain.

Read more: System Sherlock: That thinking feeling

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