Cocaine use to be deduced from fingerprints
Under the leadership of the University of Surrey, a team of British and Dutch scientists has developed a method which can determine whether the donor of the evidence used cocaine or only touched it.
The two Dutch scientists involved work as fingerprint expert and toxicologist at the Netherlands Forensic Institute (NFI). The idea for the development of the method arose when Dr. Melanie Bailey from the University of Surrey paid a working visit to the NFI.
Cocaine metabolism in the body
If someone is using cocaine, the body metabolizes it, among other things, into benzoylecgonine and methylecgonine. The body excretes these substances. Traces hereof can be retrieved from the prints and impressions left behind by our fingers.
Measuring metabolites
The researchers measure the presence of these metabolites. Because they specifically measure these particular substances, they can make statements about whether someone used the drug or whether he only touched it. If the donor of the fingerprint only touched the cocaine, it is the cocaine itself that is measured, and not its metabolites. The analysis does not damage the fingerprint.
Results compared with saliva test
The researchers used mass spectrometry – a method measuring the chemical characteristics of materials, including those in very low concentrations – in order to analyse the fingerprints of individuals in a rehabilitation clinic. They compared the results of these measurements with the results from saliva tests to see whether the results were the same.
No fiddling possible
In addition to the fact that blood or saliva is no longer required to demonstrate cocaine use, the major advantage is that the method cannot be fiddled with or falsified. “The identity of the suspect is enshrined in the source of investigation: the fingermark,” says fingerprint expert Marcel de Puit.
Analysis equipment is in Surrey
The equipment used to perform the analysis is owned by the University of Surrey. Any analyses will therefore be performed in Surrey.
Publication in analyst
The results of the study will be published today in the scientific journal Analyst.