Different Methods Used To Collect Fingerprint Evidence

Different Methods Used To Collect Fingerprint Evidence

Describe the different methods used to collect fingerprint evidence from hard/non-absorbent surfaces and soft/porous surfaces.

In crime investigation, the investigators use different techniques to collect evidence from the crime scene. The investigators use different techniques to collect fingerprints from hard and nonabsorbent surfaces. One of the techniques is using the powder technique to identify the latent prints on hard surfaces, such as glass, plastic, and metal. When using this method, the powder is spread or deposited on the targeted surface using the magnetic powder technique and spread evenly over the surface using the magnetic force (Girard, 2011). While using the powdered technique, the investigators use a contrasting color with that of the surface to attain better visibility. The second technique that is used in collecting fingerprints from a hard surface is superglue fuming. This chemical process helps expose and fix fingerprints on hard surfaces (Girard, 2011). This technique entails using the airtight tank known as a fuming chamber to heat the superglue that releases a gas that sticks to the oily residue of the fingerprint, thus creating a clear image of the fingerprint.

The collection of fingerprint evidence from porous or soft surfaces also comes with different techniques since the powder and the superglue fuming are not applicable on such surfaces. One of the techniques used on porous surfaces such as fabric, unfinished wood, and paper is the bus of chemical methods such as iodine fuming, silver nitrate, or ninhydrin (Girard, 2011). When using these chemical techniques, the chemicals come in contact with the chemicals present in the fingerprint residue, such as fats and natural oils, thus making the fingerprint more visible. For example, the iodine fuming technique occurs in the fuming chamber where solid crystal iodine is heated up to create vapor that sticks to the fingerprint’s oily residue (Girard, 2011). On the other hand, the silver nitrate technique, when it is exposed to the latent prints, reacts with the chloride of the salt particles in the fingerprints residue fo0rming silver chloride. When exposed to ultraviolet rays, the silver chloride turns black or brown, thus making the fingerprint on the surface visible.

References

Girard, J. (2011). Criminalistics, Forensic science, crime, and Terrorism. 2nd Ed. Jones &   Bartlett Learning.

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Fingerprint Collection Methods

Describe the different methods used to collect fingerprint evidence from hard/non-absorbent surfaces and soft/porous surfaces.

Textbook:

Criminalistics: Forensic Science, Crime, and Terrorism (Check chapter 6 – Fingerprints)
James E. Girard, 2017
Jones & Bartlett Learning
ISBN.13: 978-1-284-14261-7