Footprint Analysis:-

Evaluation of two-dimensional footprint impressions for comparison purposes are carried out in the field of forensic identification by one or more of the following methods; overlay, Robbins, Gunn, Rossi and the Optical Centre Method.

Three methods for barefoot examination are commonly employed–

A.) Gunn Method: One such method devised by Gunn involves taking multiple linear measurements of the footprints that are being compared. Gunn's basic method involves drawing six lines, five of which come from the rear foot and extend to the apex of each digit. A sixth line is then drawn across the ball of the foot at the widest area.

B.) Optical Centre Method: A distinct point on the foot is identified and concentric circles are drawn in its most suitable location. This point is then isolated and then connected to other recognized regions of the footprint by means of lines.

Cartridge Cases

📌 Cartridge cases are usually made of brass, a composition of 70% copper and 30% zinc.

📌Less commonly, they are made of steel or aluminum.

📌 Zinc andplastic materials have been used experimentally.

📌 Brass, plastic, and paper are used for shot-shell tubes.

📌 The main function of the cartridge case is to expand and seal the chamber against rearward escape of gases when the cartridge is fired. When a brass cartridge is fired in a weapon, the gas pressure produced by the burning of the propellant expands the case tightly against the walls of the chamber. If the brass is tempered to the correct hardness, it will spring back to approximately its original dimensions and make the case easy to extract. If the brass is too soft, it will not spring back and will make extraction difficult. If the brass is too hard, brittle, it will crack.

👉 There are three general shapes for cartridge cases: 🕵️‍♂️ Straight, 🕵️‍♂️ Bottleneck, 🕵️‍♂️ and, Tapered.

Almost all pistol cartridges are straight, whereas almost all rifle cartridges are bottle-necked. The bottle-neck design permits more powder to be packed in a shorter, fatter cartridge than would be possible in a straight cartridge, where the lumen is approximately the diameter of the bullet. Cartridges with tapered cases are virtually obsolete.

Ecotoxicology

Q:- Why soil is considered as an Evidence? Ans:- Forensic soil scientists consider soil as any earth material that has been collected accidentally or on purpose and is related to the problem they are investigating. Though the technology isn’t perfect, soil forensics is considered as an important wing during investigations. Soil in includes rock, minerals, vegetation, glass, paint, asphalt, etc. The presence of these objects in that area helps to make that area of soil unique from other areas.

Q:- What quantity of soil sample is required ? Ans:- In most forensics cases, only about one cup of the top layer of soil needs to be collected.

Q:- How analysis should be performed? Ans:- Samples are dried before testing, to prevent further decomposition of the material in the soil. 👉 At the crime lab, the forensic soil scientist conducts chemical and physical analysis tests and compares the soil samples from the crime scene location with the soil sample found on the suspect or on his or her belongings. 👉 Another test for soil is ground-penetrating radar technology (GPR). Scientist use radar energy pulses to look for breaks in the soil’s structure. GPR helps detect anomalies in the soil, where radar energy is sent back to the receiving antennae. But the drawback- it is not always accurate, especially with heavy clay soils. In the end, with the use of soil forensics and GPR technology, scientists and investigators can make connections between differences in the soil and collected evidence. By identifying by the individual characteristics of soil, investigators can use this knowledge to help solve crimes.

Formulations for Chemical Solutions

1.) Ninhydrin (Kent, 1998; Champod et al., 2004, p 239)

Stock Solution: 25 g ninhydrin dissolved in 225 mL absolute ethanol, 10 mL ethyl acetate, 25 mL glacial acetic acid.

Working Solution: 52 mL of stock solution diluted to 1000 mL with HFE 7100.

2.) Zinc Chloride Solution (Champod et al., 2004, p 240)

Stock Solution: 8 g zinc chloride dissolved in 180 mL ethanol, 20 mL glacial acetic acid.

Working Solution: 6 mL of stock solution diluted to 100 mL with carrier solvent (e.g., HFE 7100).

3.) 1,8-Diazafluoren-9-one (DFO) (Kent, 1998; Champod et al., 2004, p 230)

0.25 g of DFO dissolved in 30 mL methanol and 20 mL glacial acetic acid. Add this to 725 mL HFE 7100 and 275 mL HFE 71DE.

4.) Nonpolar Ninhydrin (Stimac, 2003a, pp 185–197)

Stock Solution: 1.5 g ninhydrin dissolved in 100 mL HFE 71IPA (may require refluxing at low temperature).

Working Solution: 15 mL of stock solution diluted with 100 mL HFE 7100.

5.) 1,2-Indanedione

0.25 g 1,2-indanedione dissolved in 90 mL ethyl acetate and 10 mL glacial acetic acid. Add this to 1 L of HFE 7100 (Merrick et al., 2002, pp 595–605). or 2 g 1,2-indanedione dissolved in 70 mL ethyl acetate. Add this to 1 L HFE 7100 (Almog et al., 1999, pp 114–118).

6.) 5-Methylthioninhydrin (5-MTN) (Wallace-Kunkel et al., 2006, pp 4–13)

1.7 g 5-MTN dissolved in 52.5 mL ethyl acetate, 50 mL methyl tert-butyl ether, 12.5 mL absolute ethanol, and 5 mL glacial acetic acid. Add this to 360 mL HFE 7100.

7.) 2-Isononylninhydrin (INON, Thermanin) (Al Mandhri and Khanmy-Vital, 2005)

4–5 g INON dissolved in 15 mL ethyl acetate, 5 mL isopropanol, and 980 mL HFE 7100.

8.) Silver Nitrate (Trozzi et al., 2000, pp 38–39)