Detecting and identifying bodily fluids at a crime scene is an important part of forensic analysis and can give people an understanding of the events that may have played out during the crime. The presence of body fluids and their location and DNA profile can be used as a part of the investigation and will often result in a conviction.
Body fluid analysis is a complex thing, and while there are numerous techniques that can be used, none are perfect. Alternative Light Sources are one tool that is often used to help people to find stains that may otherwise go unnoticed. This technique can flag up invisible or ambiguous stains and is useful for revealing stains that someone has tried to cover up, for example by wiping the area clean or painting over it. Unfortunately, ALS analysis does not clearly differentiate between certain types of body fluid, and therefore it is not a perfect technique for identifying body fluids, but it is still useful because once the potential evidence is discovered, there are presumptive tests that can be done to determine what the fluids are. If these tests are able to identify what a stain is, then the next step is confirmatory analysis and DNA analysis. Since these tests can be destructive it is important to take care to ensure that there is enough of the substance left to perform multiple analysis.
The most commonly found body fluid of interest at the average crime scene is blood. It is primarily made up of water and blood cells, and there are also metabolites, hormones and glucose in the fluid. The importance of blood in a forensic context means that there are numerous techniques used to identify it.
Luminol is perhaps the most well-known presumptive test, and …Read more