Two methods that are used to determine the scale and size of bloodstain
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There are two methods that are used to determine the scale and size of bloodstain (Saferstein, 2011). One of the methods that used is the grid method. The method involves the setting up of grid in form of squares whose dimensions are known. The square grids are placed all over the area where the bloodstains are found after which overview photographs of the grids are taken. Push-up pins and strings are used to set the grids. After that, the photographs are taken from medium range as well as close-range when the grids are arranged and when there are no grids (Saferstein, 2011). The photographic grid is a method that can be used in a selective way and it is easy to use for both experts and novice investigators. The grid is first established where walls meet, a point that is marked as the starting point. The cells in the grid are given designations and scales are provided. Photographs are taken after the grids are put in place as well as the entire wall (Saferstein, 2011). All the cells must be captured hence ensuring that the final documentation contains all the bloodstain patterns.
The second method is the perimeter ruler method. This method is also a reconstructive method that involves setting up borders using the rulers to enhance evaluation and analysis (Saferstein, 2011). The borders are set on the area around the pattern and making the marks on the blood stain on the wall. A ruler is placed close or next to the bloodstains as they appear in size and their relative positions in the photographs (Saferstein, 2011). This gives the investigator enough pieces to document. The rulers used shows the borders therefore marking the extent of the bloodstain-patterns. Moreover, the investigator needs to ascertain the level of blood flow. The bloodstains behave in a pattern that is easy to interpret and allows the examiner to trace the first place the blood was shed (Saferstein, 2011).
Saferstein, R. (2011). Criminalistics: An introduction to forensic science. Upper Saddle River, NJ: Prentice Hall.