The most common chemical method used to visualize latent prints on porous materials is ninhydrin application (Yamashita & French, 2011 p. 15). In porous surfaces, for example, wood and paper, amino acids are the reagent targets for fingerprint visualization (Yamashita & French, 2011 p. 15). In 1910, Siegfried Ruheman accidentally prepared the compound which reacted with amino acids and skin to form a purple substance (Yamashita & French, 2011 p. 15). The compound quickly became an essential tool in the identification of fingerprints in criminal justice as far back as 1959 (Yamashita & French, 2011 p. 15). Ninhydrin application is today one of the most popular methods for fingerprint identification on porous surfaces since it provides excellent distinction in ideal conditions (Yamashita & French, 2011 p. 15). In case ninhydrin application fails, another chemical technique used is Diazafluoren-9-one (DFO) (Yamashita & French, 2011 p. 19). It is a more responsive fingerprint visualization reagent than ninhydrin because it produces more detectable latent fingerprints (Yamashita & French, 2011 p. 19).
Bullets and cartridge cases should be handled with care by criminalists to prevent adding or removing markings from them which may tamper with crucial evidence such as fingerprints (Firearms Evidence That May Be Found, 2013). All kinds of evidence found in a crime scene are of great value and ruining them may have a significant effect on a case. Bullets that get lodged into walls are best collected by carefully extracting the part of the wall where it is lodges to avoid destroying or adding marks that could be vital to finding or matching the suspected shooter or firearm (Firearms Evidence That May Be Found, 2013).
A characteristic document examination unit in a crime laboratory is furnished with digital imaging instruments, microscopes, ultraviolet and infrared light sources, and electrostatic detection devices (EDD) to conduct investigative chemistry (Forensic Document Examination, 2013). To determine dye and ink constituents, liquid chromatography is carried out to detect the chemical makeup of ink on a document (Forensic Document Examination, 2013). This technique is done by making a small cut out from the document that is then immersed in a dissolvable liquid and examined (Forensic Document Examination, 2013). It is one of the small numbers of destructive methods used by document examiner because most of them use non-destructive means such as light and electrostatics (Forensic Document Examination, 2013). The inks are matched against more than 9,000 inks manufactured since 1920 (Forensic Document Examination, 2013). This information is found in the International Ink Library (Forensic Document Examination, 2013).
Obliterations, erasures, and alterations are usually not detectable by the naked eye (Forensic Document Examination, 2013). However, they can be identified through photography and other visualization devices that use infrared and ultraviolet waves of light (Forensic Document Examination, 2013). An imaging device such as the video spectral comparator (VSC) can expose inscription and texts that have been added using different ink, or have been removed or altered by taking advantage of variations in the manner that inks react to different wavelengths of light (Forensic Document Examination, 2013).
A log file is a file that records activities that have taken place (Beale, 2016). For instance, internet servers keep log files of all requests that have been made to the server. Hackers use log files to trace the activities of a computer so as to create fictitious identities and tamper with the computer processes to their advantage. Examples of areas in the computer where log files can be found include applications in form of backups, operating systems, and web browsers in form of caches (Beale, 2016).
- Beale, V. (2016). Log File. Retrieved from http://www.webopedia.com/TERM/L/log_file.html
- Firearms Evidence that May be Found. (2013). Forensic Science Simplified. Retrieved from http://www.forensicsciencesimplified.org/firearms/how.html
- Forensic Document Examination. (2013). Forensic Science Simplified. Retrieved from http://www.forensicsciencesimplified.org/docs/how.html
- Yamashita, B., & French, M. (2011). Latent print development. The Fingerprint Sourcebook, 7-67.