Polygraph & Criminal Investigation

Polygraph examinations are considered helpful in criminal investigations and ultimately, in determining culpability when it comes to a commission of an offense. This is because polygraph examinations are said to insure whether or not the person put under said examination is telling the truth or not. One of the major arguments in favor of the effectiveness of polygraph examinations is the fact that said examination is able to determine whether or not the person put under said test is deceiving the examiner. The polygraph examination is said to detect bodily changes that are connected with dishonesty and deception.

However, regardless of said fact, polygraph examinations are not universally accepted as valid and reliable. Courts generally refuse to grant credence upon the results of polygraph exams because the accuracy of said results has not yet been conclusively proven. The principle behind the use of polygraph examinations in aiding in criminal investigation is that anxiety is most often caused by an attempt to lie or deceive a person. This is linked to the detail that anxiety is detected by polygraph examinations.

However, like what is mentioned above, polygraph is not relied upon generally because its results cannot be considered as absolutely true or accurate as there are other factors and circumstances, other than lying, which can make a person anxious or nervous. The Computer Voice Stress Analyzer offers the same assistance as that promised by the polygraph examination. As has been stated, “The body has two nervous systems, the Central Nervous System and the Autonomic Nervous System. The Central system can be considered as concerning itself with those physical and sensory functions which occur at, or above the threshold of awareness” (Flood).

Said nervous systems, which are affected heavily by a person’s attempt to deceive is said to be monitored through the Computer Voice Stress Analyzer. The data provided by this system is the change in the voice of the person being examined, this change is said to have a relation as to whether or not the person is lying. However, the data coming from the CVSA, standing alone, cannot be considered as reliable when it comes to solving criminal investigations. Insuring the integrity of the crime scene is an important matter as regards collection and preservation of material evidence recovered in relation to the crime that has just been committed.

In line with this objective, crime investigators take safety measures when it comes to collecting evidence from the crime scene. Firstly, only a number of police officers should be allowed in the crime scene so as to insure orderly observation of the crime scene and collection of material evidence. As correctly pointed out, The officer should keep notes on the significant times involved in responding to the crime scene […] An effort must be made to disturb things as little as possible in assessing the situation.

Particular attention should be paid to the floor since this is the most common repository for evidence and it poses the greatest potential for contamination. […] Some things the officer should note include: the condition of the doors, windows, and lighting (both natural and manmade); if there are any odors present; if there are any signs of activity; how EMS or fire personnel have altered the scene; anything essential about the suspect […] and anything essential about the victim. Once the scene has been stabilized, the scene and any other areas which may yield valuable evidence (driveways, surrounding yards, pathways, etc.

) should be roped off to prevent unauthorized people from entering the area and potentially contaminating it (Schiro). The things abovementioned are only a few of the things that police officers should keep in mind when it comes to gathering evidence from the crime scene. After the evidence have been gathered, the same are placed in secured containers in order for them not to be contaminated before they are presented for examination. Latent fingerprints are also helpful in determining culpability for the commission of a crime.

Due to fingerprints found on the scene crime, it is easier to pinpoint the author of the crime that has been committed. Processes for enhancing latent fingerprints are employed in order to view more clearly the fingerprints collected. Initially, this is what is done by investigators, First of all, a very careful visual examination for latent prints must be made using oblique lighting (shining a flashlight flat across the surface), then direct reflected lighting (looking for prints in the glare of reflected light on the surface).

Any prints visible under either of these methods should be photographed prior to any development methods. Next, a fluorescent examination of the surface may be performed for prints with inherent luminescence, followed by photography if prints are found (“Enhancement of Latent Prints”). So also, investigators resort to use of chemicals or black powders in order to further enhance latent fingerprints. After said steps, the fingerprints printed by the use of processes, shall then be examined and will be compared to fingerprints on file in order to determine culpability for the offense committed.

If the fingerprints found on the crime scene matches with that of a certain person, then said person shall be further investigated as regards his participation in the commission of the crime. REFERENCE Patrick Flood, “Computer Voice Stress Analyzer”, <http://www. caseassist. com/deception. htm> George Schiro, “Protecting The Crime Scene”, http://www. crime-scene-investigator. net/evidenc1. html “Enhancement of Latent Prints In Blood”, <http://www. redwop. com/minutiae. asp? action=showArticle&ID=231> “Latent Print Powders”, <http://www. redwop. com/minutiae. asp? action=showArticle&ID=247>