The strange case of the phantom Phantom
A shadow falls on DNA evidence

20 April 2009

Let me tell you a disturbing story. Since the 2007 murder of a young German policewoman, Michèle Kiesewetter, cops all over Europe have been hunting a brutal and mysterious female serial killer.

DNA evidence was collected in the car in which Kiesewetter was shot and police ran a routine database check on DNA from previous unsolved cases. They discovered to their astonishment that the killer had struck as far back as May 1993 when she was apparently responsible for the death of a female churchwarden. The elusive killer was dubbed The Phantom and she was clearly a one-woman crime wave. Her DNA turned up at 40 crime scenes spread across Germany, Austria and France. She might have been responsible for six homicides and her genetic calling card was also found at the scene of low-grade break-and-enters and even on a single heroin syringe found in a school playground.

The hapless cops thought they were dealing with a problem of modern cross-border mobility – the dark downside of the EEC. A reward was offered for information leading to an arrest and millions of Euros and hundreds of thousands of hours of police work were devoted to tracking the killer down. In 2008, police released a photo-fit of the suspect based on witness sightings. Intriguingly The Phantom looked like a man. The police thought were probably dealing with a transsexual. For a time they pursued an elaborate theory that The Phantom was a heroin dealer and addict. It was the only scenario that seemed to link the disparate crime scenes. There were dark hints, based on tenuous evidential links, that the suspect was a Romany.

And then, the whole case fell apart. French police, engaged in trying to identify a burned body – thought to be that of an asylum seeker who disappeared in 2002 – took a DNA sample from fingerprints on the suspected victim’s asylum application form. The DNA was that of The Phantom.

“Obviously, that was impossible, as the asylum seeker was a man and the phantom’s DNA belonged to a woman”, said Ernst Meiners, a spokesman for the Saarbrueken public prosecuter’s office. Not to mention the fact that the asylum seeker had died before the last of the Phantom’s victims.

A second test on the fingerprints didn’t find The Phantom’s DNA. Suspicions were aroused that somehow the first sample had become contaminated.

Investigators are now certain that The Phantom was, well, just that. They suspect that batches of the cotton swabs used to take DNA samples were contaminated during the manufacture and packing process or even when the cotton was originally picked. Although the swabs are sterilised before DNA samples were taken, that process destroys bacteria, viruses and fungi, but not human cells from skin or body secretions on which DNA analysis is based. Suspicion has fallen on Greiner Bio-One cotton swabs, a product widely favoured because it came in double-sealed packaging.

The German Union of Criminal Investigators has, understandably, called for stringent anti-contamination measures and the introduction of a DNA “quality seal”.

The case of the phantom Phantom is just the latest to rock the reputation of DNA testing as an almost unchallengable form of evidence. “Judges tend to be so blinded by the shiny, seemingly perfect evidence of DNA traces that they sometimes ignore the whole picture. DNA evidence on a crime scene says nothing about how it got there. There is good reason for not permitting convictions on the basis of DNA circumstantial evidence alone”, said Stefan Konig of the Berlin Association of Lawyers.

Doubts about the unfailing certainty of DNA evidence have been building for a decade. In 2004 an investigative report in the Seattle Post–Intelligencer, revealed startling evidence of contamination of DNA samples in well-equipped US forensic laboratories. They uncovered numerous cases of contaminated tests and other human errors in Washington State Patrol’s Tacoma crime lab.

“Forensic scientists tainted tests with their own DNA in eight of the 23 cases. They made mistakes in six others, from throwing out evidence swabs to misreading results, fingering the wrong rape suspect. Tests were contaminated by DNA from unrelated cases in three examinations, and between evidence in the same case in another. The source of contamination in five other tests is unknown”, the Post-Intelligencer reported.

And the problem is getting worse. This is partly because the success of DNA testing has led to a vast increase in demand on overstretched laboratories and partly because they are now working with tinier and tinier samples. Once, a sample of, say, blood, semen or saliva the size of a small coin was necessary. Now only a few human cells, invisible to the naked eye, will do the trick. The downside is that a tiny fleck of spittle from the forensic scientist’s breath, or a few invisible cells accidentally transferred from another sample can contaminate the result.

Don’t get me wrong, DNA is a powerful investigative tool. As well as imprison the guilty it can, and has, exonerated people wrongly accused. Now, however, there are cases where it has fingered the innocent.

In the light of the gathering doubts, there’s a good case for revisiting the 2005 trial of Bradley John Murdoch for the supposed 2001 murder of Peter Falconio. Without DNA evidence, analysed under less than perfect conditions in a sub-standard Darwin laboratory, Bradley Murdoch would probably never have been convicted.

• For Nick’s take on DNA and the Falconio case go to: http://www.brushtail.com.au/july_08_on/dna_gold_standard.html