Dandruff Speck Could Identify Criminals

By Jim Kelsey

DEOXYRIBONUCLEIC acid (DNA) technology that works with a single human cell may enable scientists to catch and convict criminals from a fleck of dandruff, a licked postage stamp or a smudged fingerprint.

A breakthrough by scientists at Leeds University in northern England and Birmingham's Forensic Science Service in the English Midlands means that in future the tiniest sample left at the scene of a crime may be sufficient to bring the culprit to justice.

The extension of DNA fingerprinting could also help pinpoint rapists in a multiple rape case based on individual sperms collected from a swab. The new technology can also tell the sex of a person from a single cell.

Dr Ian Findlay of Leeds University's Department of Molecular Oncology described the development as the "breakthrough everyone had been waiting for". He said that it was now possible to conceive that there would eventually be no scientific barrier to the detection of crime. "There is no longer going to be a clueless scene of a crime. Every scene will have some distinctive evidence. There is always going to be something left behind by the criminal," he said.

The research may well be used to solve old crimes. This would depend on how cells have survived, for instance on a gun, shirt or other personal possession. It could possibly be used to solve the mystery of the identity of the culprit of the "Jack the Ripper" murders.

"You may be able to go back even further, but not probably as far as 500 years. In the end we will know only when we see the old sample," he said.

Financially supported by the Medical Research Council, the breakthrough will do away with the need for millions of cells that are needed in a sample to carry out a DNA profile or fingerprinting test.

The established method of DNA fingerprinting by forensic scientists, technically called short tandem repeat (STR) profiling, has depended on samples of 200 or more cells. The analysis then takes a week.

The new method described in the scientific journal, "Nature", is a refinement of STR profiling. Although it can be done with only a single cell, the technique provides a more detailed description of the individual than the existing analysis of larger samples. Furthermore, the analysis is done in six hours.

Using the technique, the chances of cell samples from two people producing an identical result are claimed to be 100 million to one. With further funding the United Kingdom team believes it could have the system in place for the forensic specialists within two years.

Dr Ian Findlay, Department of Molecular Oncology, Leeds University, Woodhouse Lane, Leeds, United Kingdom, LS2 952. Telephone: +44 113 243 1571. Fax: +44 113 233 4225.

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