CSI shoots real-life crime investigation in the foot

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This is not a still from a Children's Television Workshop-produced season of Dexter.

Instead, it's a shot from inside a forensic science training center at the University of Glamorgan in South Wales. The Economist visited the school for a story on "The CSI Effect"—that unfortunate legal train wreck that is the result of jury pools being simultaneously over-informed, under-informed and misinformed about forensic investigation science by prime-time cop shows. And, apparently, the same television habits that make juries expect a 100%, no-question DNA match for every case is also giving criminals ideas for evading the law.

Criminals watch television too, and there is evidence they are also changing their behaviour. Most of the techniques used in crime shows are, after all, at least grounded in truth. Bleach, which destroys DNA, is now more likely to be used by murderers to cover their tracks. The wearing of gloves is more common, as is the taping shut--rather than the DNA-laden licking--of envelopes. Investigators comb crime scenes ever more finely for new kinds of evidence, which is creating problems with the tracking and storage of evidence, so that even as the criminals leave fewer traces of themselves behind, a backlog of cold-case evidence is building up.