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Footwear evidence as the name suggests, is the foot impressions that used in connecting the culprit to the act of crime. Properly collected and analyzed footwear evidence normally leads to the culprit (Domnauer, 2007).
If the shoe or foot impressions do not bear inimitable patterns or marks, they are null and void evidence. Additionally, if the evidence can link to the real culprit, they are admissible evidence in the court of law (Fisher, 2004). In order to capture footwear evidence, gelatin lifters and plastic casts are mainly used to produce both two and three-dimensional forms of the cast impression.
How to preserve evidence
Photographed evidence is only admissible in the court of law if the prosecutors can prove that they collected and properly documented them. Repeatedly, only the authorized staff are only restricted to the evidence. All rules governing the evidence preservation is essential for legal authorities and police.
For example, an investigator should document a transfer of evidence from the evidence section to a forensic laboratory for analyses. It is a general rule that when the custody of evidence changes, proper documentation is mandatory (Pepper, 2010). Once the evidence analyses are over, the laboratory staff must make sure they have the evidence and no one tampers with. Documentation process aims at reducing theft of evidence (Pepper, 2010). It is important that all evidence will be preserved and subject to scrutiny by the defense lawyers.
Photography of the footwear evidence
In collecting the footwear evidence, white and black films are usually used, but in the case of blood stains found on the impression, the detector can shine an indirect light onto the impression. Sequences of photographs with varying light positions provide enough photos to allow proper investigation.
Moreover, scaling and adjusting images improves the image for thorough analyses of the impression. Aerosol paints provide best impressions by highlighting the footprints when it is difficult to capture visible images at the crime scene. Photographing the footwear evidence requires a special camera to capture best qualities (Millen, 2008).
Casting the footwear evidence
Making the cast of the footwear impression at the crime scenes is a special activity which requires diligence and ability. Production of the impression will help the comparison between the shoe and the impression. A dental stone is generally used as a casting stone. Dental stone is available in the form of powder, which is then mixed with clean water.
The mixture is normally poured gently into the footwear impression created on the soil. It is then allowed to set up for at least thirty minutes after which it is possible to collect as the footwear evidence (Domnauer, 2007). The impression can now be used to trace the culprit and as evidence in the court of law by comparing both the footwear impression with the real shoe. Casting has been very fruitful in providing evidence used in the criminal court proceedings.
Procedures used in examining firearms evidence
Firearms offer crucial evidence related to criminal activities. Laws governing the arms stipulate that when the firearms found at the crime scenes, it is a procedure to unload and store them in a secured place.
If the person collecting is not conversant with the best way of unloading, he or she should seek help from an expert, usually the firearms instructor or an examiner. Careless and negligent unloading will make it difficult for DNA trace or any useful evidence present. It is a general rule that all unloaded firearms are only submitted to a laboratory.
After securing the firearm, law requires a follow-up of the agency protocols recommend identification of firearms by the crime detector. The agency protocols require that the collector should inscribe his or her initials using a diamond on the trigger guard. Firearms collected from water points should also follow special handling procedures so that no evidence is carelessly destroyed.
A closer check on the trigger can show the real finger prints of the culprit, but finger prints are invisible in case the culprit had used hand gloves (Domnauer, 2007). Evidence such as the fingerprints and DNA can only be traced if the firearm is in a safe custody or under proper control.
If there are blood stains, tissue and hair, it is a mandatory that they are closely examined by a qualified laboratory technician. The examiner must wear mask and hand gloves when collecting DNA found on the firearm. If there is more than one firearm, different gloves are strictly worn for each case.
To ensure a safe custody of the evidence and the firearms, the detectors should always wrap in a tamper proof paper and stored in a box that is only designed for firearms. Unloaded firearms are carefully marked, identified and packaged separately. Firearms examiner should always be aware of the state of packaging and storage before submitting to the laboratory for more examination. Dismantling and unloading of guns is not applicable to shotguns and rifles because they can tamper with the value of evidence (Fisher, 2004).
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Domnauer, T. (2007). Crime scene investigation. Columbus, OH: School Specialty.
Fisher, B. A. J. (2004). Techniques of crime scene investigation. Boca Raton, FL: CRC
Millen, P. (2008). Crime scene investigator. London: Robinson.
Pepper, I. K. (2010). Crime scene investigation: Methods and procedures. Maidenhead: Open University Press.