Crime fighting chemicals

A unique partnership between an organic chemist and the US Secret Service has led to the improved analysis of fingerprints at crime scenes. The new process is said to be less damaging to evidence, more sensitive and less expensive for law enforcement agencies.

Chemicals used to detect fingerprints must be gentle and sensitive – the smudge left on a surface by a passing finger contains, on average, just one millionth of a gram of amino acids, fatty acids, glycerides, urea and salts – and yet inexpensive enough to be dusted on evidence at crime scenes.

Madeleine M Joullie, Professor of Chemistry at the University of Pennsylvania and her Secret Service colleagues appear to have filled a crime fighting niche with new class chemicals known as indanediones.

Indanediones are said to fit the bill better than any fingerprinting compounds currently available.

Despite other technological advances in law enforcement, the materials used in this staple of crime-scene investigation have remained remarkably low-tech over the years.

While various alternatives exist, the fingerprinting chemical most used by law enforcement agencies the world over is ninhydrin, a compound that has been used in law enforcement since the 1950’s.

Another fingerprint-finding compound now used by some police departments, diazafluorenone is another fingerprint-finding compound commonly used by US police departments. It’s cost, however, is said to be prohibitive at $40 a gram.

The indanediones developed by Joullie can be produced for a fraction of that cost through a relatively straightforward, reliable sequence of reactions.

Low cost isn’t indanediones’ only advantage. When combined with the amino acids in a fingerprint, indanediones’ heightened sensitivity causes them to glow even more brightly than diazafluorenone. Indanediones are also significantly easier to use.

‘To avoid thermal decomposition of evidence, diazafluorenone prints must be developed with a carefully timed application of a high-temperature, dry-heat system,’ said Joullie. ‘In the case of indanediones, only steam heat in necessary, which does not damage the evidence.’