Methods used in Crime Investigation

Paper Summary:

This paper discusses various tools that are used today in criminal investigation. It focuses on the polygraph, voice stress analyzers, ways to preserve the integrity of the crime scene and DNA analysis and fingerprints. It also looks at the history of the methods, how they are used in crime investigation and their validity and integrity as investigative tools.

Table of Contents:
Polygraph
Crime Scene Integrity
DNA Analysis and Fingerprints

From the Paper:

"Other methods such as ninhydrin coloring and luminescence detection suing DFO reagent are more sensitive and hence effective even with lesser traces of the substrate (range of 100 to 200ng and 1 to 10ng respectively) In some cases after initial treatment with ninhydrin, zinc and cadmium salt treatment can be used to enhance luminescence. Physical development can be used separately or in addition to DFO treatment. This process is similar to the common photographic development process using silver nitrate solution. (Dr Chris Lennard (2001)). Arches, whorls, loops and composites are the four different patterns under which fingerprints are classified. Earlier, comparing fingerprints used to be manual and time consuming. Today, however computers can match a persons fingerprint with more than a million fingerprints stored in its database in a few seconds. This is possible because the FBI and the National Crime Information Center (NCIC) use automated fingerprint identification systems using the standardised fingerprint classification system called the FPC. The computer generates a geometric graph based on the positions of the ridge endings and the ridge branching. Experts then compare closely matching results from the computer search for exact identification. (Courtroom Television Network)."

Sample of Sources Used:

• Kevin Bonsor, "How Lie Detectors Work", Retrieved on 21st May 2007, from http://www.howstuffworks.com/lie-detector.htm
• EPIC, "Polygraph Testing", Retrieved on 21st May 2007, from http://www.epic.org/privacy/polygraph/
• BCSSE, "The Polygraph and Lie Detection", Retrieved on 21st May 2007, from http://books.nap.edu/openbook.php?record_id=10420&page=212
• Gerry Everding (2004), "Research casts doubt on voice-stress lie detection technology", retrieved on 21st May 2007, from http://news-info.wustl.edu/news/page/normal/669.html
• University of Missouri, "Computer Voice Stress Analyser", Retrieved on 21st May 2007, from http://campus.umr.edu/police/cvsa/cvsaintr.htm

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