Question: How many areas are there and which one do you specialise in?

Craig McKenzie answered on 15 Jun 2011:

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Hi Floydy97,

Sue has given a very good and comprehensive answer but i might like to add a few things as well. I am a forensic chemist specialising in fire scene examination, analysis of drugs and abuse and toxicology samples and alcohol analysis. Most forensic scientists are expert in a small number of areas but have a basic understanding of other areas too. We cant know everything about everything and that is important to know.

In a forensic laboratory you can generally divide the areas into Chemistry and Biology. Sue has explained the biology bit very well – As for the Chemistry area it would be split into further smaller areas:

Chemistry: General Chemistry, Drug Analysis (the analysis of drugs of abuse like cocaine, heroin, cannabis, ecstasy – where we prove the drug is what we think it is and then work out how strong it is) and Toxicology (where we have samples like blood, urine or even the liquid from inside your eyeball (!! This is called the vitreous humour which is a funny name for something so icky) from people who have died suspiciously or have taken a deliberate or mistaken drugs overdose. Sometimes we take blood or urine samples from people have been taking drugs or drinking alcohol whilst driving and we look to see what is in their bodies.

General Chemistry contains all the other chemistry bits that don’t fit into the other two and you never know what you are going to get asked to do!

General Chemistry:
Fire Scene Investigation, analysis of common fire accelerants (things like petrol and diesel and other liquids that make a fire burn really well) we can recover burnt objects from a fire scene and can find tiny traces of accelerants – fire scenes are one of the most difficult and dangerous crime scenes to investigate – most of the evidence is either destroyed or hidden and we have to work like archaeologists to find the evidence, sometimes buried under collapsed buildings or rooms. Fire is often used by criminals to destroy evidence – to remove any evidence that the suspect has left behind or to burn bodies so that the cause of death is difficult to figure out, or sometimes fire can be used just to try to kill or injure people. In some cases fires can just be horrible accidents that look suspicious at first.

paint and glass – these are most commonly analysed in crimes like road accidents (normally hit and runs) or burglaries but sometimes assaults too (i worked on a case where paint found on a baseball bat linked a suspect and a murder victim), The machine we use for glass analysis has the best name. It is called the ‘GRIM’ which always makes me laugh but stands for Glass Refractive Index Measurement..

For shooting incidents or in a crime where a gun is thought to have been handled, most scientists are involved in the recovery of what we call gun shot or firearms discharge residue (GSR/FDR). When someone fires a gun, is nearby when a gun is fired or has handled a gun that has just been fired might pick up little pieces of chemicals found in the bottom of the bullet which explodes when the trigger is pulled. We use very careful techniques to recover these special particles from hands, clothing or suspects. I have been involved in quite a few cases where we examined cars which have been used a getaway cars in armed robberies and have then been dumped. We can often prove that a gun has been in the car by taking lots of sticky tapings from inside the car which will pick up the gun shot residue if it is there. This also works for explosives and i have been involved in some terrorism cases too. Back at the lab we use a very special (and expensive) microscope to look at the particles – it’s called and Scanning Electron Microscope (SEM) which is very cool and you get amazing pictures from it. Here is a picture of a gun being fired and you can see the cloud of particles when the trigger is fired. It also shows pictures of the particles that can be recovered from those close by:

http://www.gunshotresidue.com/forensic.htm

Some other scientists can also study the path of the bullets when they have been fired or the markings found on bullets after they have been fired (sometimes they are removed from the victims by a pathologist or a doctor).

Here is a website with some other info: http://www.nabis.police.uk/

As well as these there are people with other skills that can be involved in criminal investigations but who do not work in a forensic laboratory:

Entymologists – these guys study bugs and maggots that might be found on a body if it had been lying undiscovered for a long time – Shane is an expert in this area of forensic science.

Palaentologists – these guys study the tiny grains of pollen that may be found in crime scenes and these can sometimes prove very useful when you want to know where the victim may have died and where the body is eventually found.

You can also have experts in handwriting or documents examination, people who look a footwear marks, fingerprnts experts like Richard and forensic anthropologists like Anna – the list goes on!

This has of course left out those specialists who spend every day going to crime scenes recovering evidence and recording them carefully and who often ask forensic scientists to come to the crime scene if there is a need for specialist advice or in general if the crime is very serious. These people are, scenes of crimes officers (SOCOs) photographers, crime scene managers and the like.

So you see there are many types of scientists who can work in science cases relatedf to criminal investigations (forensic science). We each know a lot about our own areas but we have to work closely with people who know more about other subjects than we do.

So in any one case i might work with a forensic anthroplogist like Anna, DNA and biology experts like Sue and Shane and fingerprints experts like Richard. It’s all about working together to get the best results and a lot of science is like that – it makes it more fun to work with other people too.
I hope that helps – let us know if you have any other questions!