This is not unexpected, as any human endeavor necessarily involves some chance of error. Some studies have shown that different examiners occasionally come to different conclusions when assessing the same evidence. If there is enough detail in the latent print, the examiner will carefully compare the features of the two prints and determine, based on training and experience, if the prints are likely to have come from the same person or from different people. Latent prints are often partial, distorted or smudged, so the first step is to determine if there is sufficient detail in the latent print to make a comparison. A trained fingerprint examiner makes that assessment by comparing details including the shapes that the ridge lines form and where the lines end or split. Fingerprint analysis generally involves comparing fingerprints found at a crime scene - called latent fingerprints - with fingerprints from a known individual and assessing how similar they are. We know that criminals can leave these traces behind them after they commit a crime, but how easy is it to detect them? And how do experts record them for later analysis? To read about preserving impression evidence, pry open the next page.What is fingerprint analysis? Investigators have been using the results of forensic fingerprint analysis to solve crimes for more than a century. All of these tools leave distinctive marks that investigators can easily identify - almost as if the tool itself were leaving a fingerprint at the crime scene. Suspects typically use wire cutters, crowbars and screwdrivers to cut and pry their way into windows and doors. Lastly, tool marks are created when a tool comes into contact with another object or surface and leaves a significant impression. Further inspection, however, can reveal more - defects and wear on a tire tread caused by nails, gravel, patches and alignment problems can identify a unique set of tires. Initially, a tire mark can tell an investigator the brand of tire a criminal used, but that only narrows things down slightly. Tire marks work the same way as footprints, although tire marks are much easier to identify. Still, stains and other residue will leave two-dimensional marks and create a recognizable image.Ī forensic scientist analyzes tire tracks taken from the scene of a hit-and-run car crime. Carpet or grass, however, will rebound and regain a flat surface more easily, and an impression on these types of surfaces will only last a short time. If you've ever driven a car through the mud, you've probably seen the clear scar the tires have left in the earth. Shoe impressions on materials such as soil, sand or snow can produce a largely three-dimensional footprint. Unfortunately, residual static charges don't last very long and can be easily upset, so forensic experts rely more on the deformation of surface areas. Simply sprinkling fingerprint dusting powder over recent footprints will attract the powder to the charge and create a visual image of the impression. Perhaps most surprisingly, even clean, dry shoes can leave an impression on a hard surface by creating electrostatic charges. But several things happen when our shoes touch the ground. Unless we're tracking in mud or rainwater and making a huge mess, it's nearly impossible to see the traces we leave with each step. When we walk into a room, we're usually not thinking about our footprints.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |