Analysis of Glass Use in CSI
Glass is often encountered in criminal investigations and hence is very useful evidence. Analysis of glass comes about when during a break and enter, glass is broken. The fragments of glass will be scattered in the body of the suspect. After collecting fragments of glass at the crime scene, they are taken to the crime lab, where perhaps they will be hopefully connected to the broken glass at the scene by the crime laboratory technician. The establishment of this link can be through looking into the various glass properties such as refractive index and density. When a glass is broken, small and sharp pieces scatter over a wide area. Large pieces are usually found around the original location of the glass plane and in the direction of the blow. Also, in the direction of the blow, small shards can be thrown up to 10 ft. from the pane (Harshey et al., 2017). Hundreds of shards are often inevitably caught in the clothing or hair of the person who broke the glass in case a violent blow did this.
Different Types of Glass Studied in CSI
There exist many kinds of glass. However, three main types are usually encountered in a crime scene. The soda-lime, ordinary window, or bottle glass is the most common kind usually found in the crime laboratory. When heated to a temperature of more than 650 degrees, the soda-lime glass starts to soften. This can prove useful in the investigation of fires like in a case where the windows of a building are found to be deformed after a fire. Besides, there is the laminated glass. This glass is made of a two layer of soda-lime glass placed betwixt a plastic medium. As a result, the glass has great strength and hence is used in the windshields. The third type of glass likely to be found in a crime scene is tempered glass. It is meant to withstand fracturing and hence does not shatter into pieces when it breaks. As a result, the impacts on the car do not cause dice to cause jugged edges. The probability of finding glass evidence on the perpetrator, however, decreases over time since the fragments of glass caught in his or her clothes and hair begin to fall off within the first hour. The rate of falling will depend on the type of cloth the perpetrator is wearing at that particular time.
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Comparison of Glass Fragments Help in CSI
Glass fragments in a crime scene help to solve hit and run. Typically, glass fragments are used to link a suspect to a crime. For example, there may be a breaking of glass in a crime scene. As a result, the perpetrator or suspect may be found processing a piece or some pieces of glass. When these fragments reach the crime laboratory, the technicians will attempt to pair the broken window at a crime scene with those pieces. Typically, the comparison is made by looking into the characteristics of glass, such as refractive index and density. The results are matched or compared to one another. Besides, the non-optical properties can be used to make this comparison. This includes the surface texture, curvature and special treatment of the glass fragments.
Comparison of Glass Fractures Helps in CSI
To study the glass fragments from a crime scene, there needs to be a determination of the direction of impact based on the point of view. For instance, it is essential to gain knowledge on what direction a bullet came if it travelled through a glass window. It is essential to determine if the bullet was fired in the home for example, or outside the home or if it was a close shot of it was shot from a distance ( Gardner & Krouskup, 2018) . This will help the forensic to narrow down the perpetrators. Besides, it can be critical in reconstructing the crime scene. Also, this analysis allows forensic analysts to make some sort of determinations. The first thing to check for if all the fractures of glass are present is the hole made by the projectile or the load. This can be a bullet, harmer or anything with great tensile strength and the exit side is usually wider.
References
Gardner, R. M., & Krouskup, D. (2018). Practical crime scene processing and investigation . CRC Press.
Harshey, A., Srivastava, A., Yadav, V. K., Nigam, K., Kumar, A., & Das, T. (2017). Analysis of glass fracture pattern made by. 177 ″ (4.5 mm) caliber air rifle. Egyptian Journal of Forensic Sciences , 7 (1), 20.
