Question: what other scientific areas do you cover in forensic science

Sue Carney answered on 16 Jun 2011:

Hi electroleft.

There are lots of areas in forensic science. I won’t list them all here because we had a similar question previously and gave lots of information in those answers which you can read here: http://ias.im/54.202

In my particular area, I cover all the different body fluids. Blood, saliva, semen, urine, faeces, vomit etc. There are lots of chemical tests and searching techniques for each type of body fluid. It’s important to know how all the tests work and what the limitations of the tests are. Some tests are ‘presumptive.’ That means that other things can also give a positive result in those tests, not just the body fluid we’re searching for. So a positive result for a presumptive test might indicate that that body fluid is present but not confirm it. Other tests are confirmatory, so they specifically identify that body fluid.

As well as body fluids, I also have to have a detailed knowledge of DNA profiling tests, including which body fluids will give a good result, what to do if we detect a mixture of DNA that contains more than one person’s DNA, and how to deal with samples that have very small amounts of DNA in them, for which we use a much more sensitive method of DNA profiling that can sometimes give us a DNA profile from an item that has been touched by a person.

Finally, I also have the experience to answer questions about damage – especially to items of clothing. I can use these skills to try to say how the damage was caused (was it from tearing or cutting for example), how recently it happened and the extent of force that might have been required to cause it, although that’s often difficult to quantify.

I need to have a general awareness of the other areas of forensic science (as detailed in the link I added earlier) because there may be more than one type of evidence on an exhibit and I’ll need to discuss the examination strategy for that item with the other expert who’ll be working on it, to decide which is the best order to do our tests so that we don’t ruin each other’s evidence.