'I'm a how man, not a why man' - CSI Miami.
If you watch CSI programmes you might think that the various tests and techniques that can be used make the job of solving crime easy. You would be wrong. In TV shows photoluminescence, where chemicals and light are used to find body fluids, light the room up in neon blue. In reality the experiement is much harder and more subtle. However, we can demonstrate it in our CSI team building event and it is very interesting.
Fingerprints are also much more difficult to life in the field. Fingermarks are often smudged or incomplete and the act of lifting them can destroy them. Most testing will be done in the lab, but we do field tests. It is interesting to see how difficult it is.
Forensics generally is going through massive changes. Fingerprinting and techniques such as facial and body recognition have been used since the start of the 20th century but the really exciting development is happening in DNA, which has been really developing since the 1980s. The police are now solving hundreds of cold cases going back decades thanks to new developments.
Here are a few points in the forensic area of murder investigation.
Photographic examination is better than taking a plaster cast because plaster can expand when drying by between a half and full foot size. The depth of a footprint can indicate the weight of the person leaving the print. This can help in cases where someone uses a larger pair of shoes, for example a woman posing as a man or someone trying to set someone else up for a murder. Footprint depth can also show whether someone walks with a limp.
Dew and insects under a body give an immediate indication that it has been there overnight.
If a body is dragged it may collect leaves and dirt in unnatural places, for example in a collar or pocket.
High velocity bullets go straight through. Hunters tend to use them because they make a clean kill. The rounder the bullet the more tissue damage it will do. Hollow point bullets are particularly nasty and will do a lot of internal damage. Gunpowder leaves a residue trace on clothing and skin which can identify a killer and the test is fairly easy. We recreate this in our CSI event.
Now look at poisons.