Finger Print Identification - IELTS Listening Answers & Explanations

Welcome to our technology lecture. I am Professor John Stewart. Last week we talked about astronomy. Today, I'd like to introduce you a lecture on finger print identification. Identifying finger prints has been a vital tool in the crime fighter's arsenal for more than a hundred years. According to the record an Argentine police officer was the first one to use the method of criminal identification in 1892. He proved that a woman was guilty of murder because a bloody finger print at the crime scene had to be hers. Nowadays, finger print forensics are about to take a huge leap forward from physical to chemical. Scientists have unveiled a new technique that can extract a lot of information.

So the physical print itself is identification, but there's a lot of information that's contained in those finger prints. Then, what are the main functions of finger print identification technology? Scientists have summarised its four functions: the first one is to create image, which one is an important beginning; and then the second one is to get characteristics; and the next is to keep information and the last one is to contrast data. Meanwhile, some experts have pointed out that finger prints are actually a transfer from our fingers onto an object to chemicals. Those chemicals could be things that we've handled already recently, or they could be secretions: oil and sweet from our bodies.

We can use a technique named mass-spectrometry to identify all those substances even they are in tiny amounts. Graham Cooks from Purdue University in the United States has explained how the technique works in his paper. As he points out, experts can get the information in a very, very simple and straightforward way using a new type of mass-spectrometry. His experiment is to make a fine mist of a solvent like water and to provide an electrical charge to those little droplets that constitute the mist and to direct that at the object, for example, a finger print, and then spray that in a very fine fashion with high precision, as these droplets arrive, they create a thin film, liquid obviously, on top of that surface. The chemicals in the finger print dissolve in that liquid, another drop arrives, splashes against the film, creates smaller droplets and those smaller droplets are sucked up into an instrument, the mass-spectrometer, then dried off and they're identified. The whole process of recording the mass-spectra of a single spot on a finger print takes a fraction, a few tenths of a second.

So the last step in the experiment then is to create an image of the finger print that is not to keep the spatial information but to represent only one of the chemicals. Experts could build up different layers of colours for different chemicals. And so in the mass-spectrum, it doesn't matter if experts don't have to say in advance what molecule they're looking for, they can just screen through all of this data and find out what drugs, virtually any type of organic or even biological molecule can be seen. Maybe someone will ask if this equipment can be taken to a crime scene or can only be used it in a lab. The answer is yes. We can take the equipment to a crime scene. Actually, scientists have built as series of small mass-spectrometers, the smallest of which is merely a four kilograms instrument so that's hand portable, you can walk around with it and you could take it to a crime scene and do the experiment that we've been talking about.

Among this chemical information of the finger prints that our scientists have collected we can find more information about the people themselves. Many scientists including Graham Cooks are more interested in this new research field: some scientists have begun to do research on whether the distribution of the compounds are the result of people's metabolism; as we all know, more and more people are worried about their metabolism which is very important for people's daily life; some others focus on the topic about whether we can find out people's age and their sex, if we can, that will be a great contribution to medicine, law or other fields; the third one is that some experts even study on where the things in fact are going wrong in terms of people's own biology. That of course will be a huge project, but it is necessary to life. I really hope that if you're interested in this topic you could join in our research group.

Of course that's a research area that we don't have all the answers here. But we certainly have a mountain of data coming in, which should enable us to address these questions.

OK, if you want to know more information about finger print identification you can read our journal online or attend a lecture on next Friday at The University of Bath or visit our website, the address is... (fade)