Helping police find forgers

29 November 2017

Professor James Curran
Professor James Curran

Professor James Curran is working with American researcher Dr Patrick Buzzini of Sam Houston State University on a project that promises to help police identify the origin of fake banknotes through the printers used to make them.

Many of the banknotes are forged using high-resolution inkjet printers that can forge “quite plausible currency,” explains James, a forensic statistician. The pair aim to develop chemical profiles that will reveal what type and model of inkjet printer was used to produce a counterfeit bill.

Typically, suspect documents are compared to a reference sample by optical inspection, usually followed by thin layer chromatography, which separates the components of a substance, to address questions about their origin.

This investigation will add another method, Raman spectroscopy, to determine to what extent doubtful documents can be linked back to a source based on the three main colour components of the inkjet printing system, including mixes of cyan (blue), magenta (crimson) and yellow.

The US Secret Service has supplied around 100 fake notes that Patrick will survey using Raman spectroscopy. James will be handling the statistical side of this research, and will develop a novel statistical approach to analyse the complex data that will emerge. He has just been to Texas to advance the project and teach Patrick’s class some aspects of experimental design.

While at Sam Houston State University, James was given a tour of the body farm that belongs to the institution. Bodies donated to science are left in the outdoors to decompose, with most of the research carried out there related to outdoor crime scenes.  

Says James, “An investigator, for example, might be interested in how a body would look if it had been burned and then left in the woods under corrugated iron for six weeks. Some of the cadavers we saw there had been burned and then left to decompose.”

The body farm – more officially named the Southeast Texas Applied Forensic Science Facility – is the largest of seven in the United States and one of two in Texas. It’s open only to scientists and law enforcement staff. At present, the science of decomposition is a relatively new discipline – the world’s first body farm was opened in Tennessee in 1972 – and James says there is scope for more statistics to be used in the studies conducted in them. “The issues are that the decomposition process is highly variable, and of course that there is a limit to how many cadavers can be used in such experiments.”