High price of the real colour of money...

SCIENCE ON FRIDAY:

Dr Bob Ardrey (former senior lecturer in Analytical Chemistry and Forensic Science, now a senior research fellow in the School of Applied Sciences, University of Huddersfield) writes about drugs and money...

Where do the illicit drugs on the banknotes in your wallet or purse — yes, yours — come from?

Many people do not realise that more than 99 per cent of banknotes in general circulation are contaminated with illicit drugs, particularly cocaine.

The presence of drugs on banknotes is unlikely to lead to your immediate arrest – but the police usually attempt to use these findings as a link between the individual holding the cash and illegal activities.

Since the Proceeds of Crime Act 2002, there has been an increased interest by other authorities, such as the Serious Organised Crime Agency, in proving such a link – so a confiscation order can be issued and the proceeds of illegal activities removed.

An application for a confiscation order is actually made under civil law, requiring the link to be proven on the balance of probabilities (rathr than the criminal law requirement of “beyond reasonable doubt”).

So, does finding drug contamination on banknotes always provide this incontrovertible link?

Forensic investigation can show that seized banknotes (and occasionally mobile telephones and motor vehicles) are contaminated.

The finding of contamination certainly demonstrates that there has been contact between the banknote and the drug, but does this provide the necessary direct link between an individual and illegal drug activity the courts require?

Well no, obviously. The tests can’t provide proof of how, where or when that contact occurred. There may be a perfectly innocent explanation associated with the lifestyle or business of the individual found with the cash. The currency itself may have picked up the drugs in ordianry circulation - we have heard of contamination being passed on by bank counting machines, for example.

The note-test method of choice is both exacting and highly accurate, involving the vaporisation of materials on the surface of the banknote and the analysis of that vapour by means of that ‘CIS Miami’ favourite, mass spectrometry.

This allows individual notes to be examined - important when an expert witness assesses the significance of any findings. Modern mass spectrometry techniques are also pretty rapid, which means large numbers of notes can be examined quickly.

Mass spectrometry is well accepted in the forensic community; it allows the identification of very small amounts of a drug. — a typical level on one banknote is less than a ten-thousandth the weight of a grain of sand.

Interpretation of the results involves consideration of the proportion of contaminated banknotes and the level of contamination on each. The major drugs of interest are cocaine, heroin, THC — the active constituent of cannabis; amphetamine and Ecstasy.

Examination of a large number of banknotes in general circulation shows that cocaine is found on virtually all of them, while the other four are less common.

As with all forensic inquiries, three issues must be considered by an expert witness after banknotes contaminated by drugs have been seized:

::Can we demonstrate that contamination hasn’t been introduced during seizure, storage or transport to the laboratory for analysis, or even during testing?

::Is the analytical method valid?

::Assuming it is, how do we interpret the results?

Unless the possibility of contamination after during and after seizure is excluded, the other questions above are irrelevant.

It is rare that the finding of contaminated banknotes is the only piece of evidence used to decide the guilt or innocence of an individual but it does help provide a more complete picture that will hopefully lead to a just verdict.