CSI: Where is the science?

July 29, 2009 by Tim
Filed under: Entertainment, science

Forensic science has been catapulted into popular culture through the enormously popular CSI TV series franchise. Beautiful, smart and interesting people swoop on a crime scene and in the next 45 minutes collect the most minute traces of evidence, analyse it, match it to suspects, and finally arrest the perpetrator. The evidence is always overwhelming and the baddie has no alternative but to confess to the crime.

CSI Las Vagas - Laboratory

I guess one has to be pretty naïve to think that’s how it really happens. In reality CSI forensics is slow, methodical and hard work. A toxicity test that will take minutes to complete in the show could take several months in a real laboratory. The real equipment bears no resemblence to the hyper-cool halographic examination tools or the amazing imaging equipment that can transform a tiny blurred, oblique image into a perfectly sharp masterpiece.

Yet it appears that there’s even a phenomenon named after this unrealistic idea of forensics: the CSI Effect. And there is some evidence to suggest that it’s not only the public who are taken in by it, but also policemen, prosecutors and jurors – and criminals.

But even in the real world, how scientific is forensis anyway? Popular Mechanics has published an interesting article, CSI Myths: The Shaky Science Behind Forensics, which illustrates that most of it was not developed by scientists but by cops. In a related article, even that gold-standard of forensics, fingerprint matching, is shown to be inaccurate and unscientific.

A 2006 study by the University of Southampton in England asked six veteran fingerprint examiners to study prints taken from actual criminal cases. The experts were not told that they had previously examined the same prints. The researchers’ goal was to determine if contextual information—for example, some prints included a notation that the suspect had already confessed—would affect the results. But the experiment revealed a far more serious problem: The analyses of fingerprint examiners were often inconsistent regardless of context. Only two of the six experts reached the same conclusions on second examination as they had on the first.

The other familiar modalities of ballistics, trace evidence and even biological evidence are also shown to be largely unscientific. This is actually quite shocking.

As one would expect, the closer the techniques are to real science, the more reliable they are. So, for instance, one can have complete confidence in DNA profiling.

But back to the TV show: do the writers not understand how GSM networks work? They continue with the standard old land-line telephone bromide of keeping the fugitive on the line long enough to do a trace. Obviously, as soon as a cell phone attaches to a GSM network its position is known – albeit approximately. No delay – this information is known immediately. So why do they persist with this nonsense?