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February 17, 2022 - BY Jewel Mary Saju

Recent Advancements in Impression Evidences

Impression evidence is those evidence created when an object is pressed against another material with sufficient force. Some of the impression evidence commonly encountered at the scene of the crime are fingerprints, footprints, lip prints, ear prints, bite marks, tool marks, etc. With improving and developing technologies in the field of impression evidence, different methods have been adopted to identify and develop them. Some of the recent advancements pertaining to this evidence are as follows: 

Fingerprint Impressions

A fingerprint is a vital tool for identifying the use of illicit drugs by a criminal. Recent studies have shown that using mass spectrometric devices or portable mass spectrometers at crime scenes, it is possible to detect the residues of illegal drugs such as cocaine. It is also possible to identify whether the particular drug was ingested or it was simply touched by the suspect where the traces remained on his fingers based on the drug metabolites.

Fingerprint Molecular Identification (FMI) Technology utilizes mass spectrometry in order to identify gender biomarkers as well as narcotics and nicotine metabolites along with some legal medications for criminal convictions.

Scientists are able to distinguish the age of a print that is between a day/ week old, a week/month old, and a month/four months old. This method is based on the movement of biochemical molecules residing in fingerprints from the ridge area to the empty furrow regions of fingerprints. However, this concept is still under study.

Recent researchers have shown that the race of an individual can be determined with the help of minutiae present in the prints.



Recover Latent Fingerprint Technology (LFT) is a novel technique used to reveal fingerprints on surfaces exposed to a very high temperature such as discharged ammunitions (cartridge cases or bullets), burned vehicles or corroded materials, and on surfaces that have been deliberately washed off. This technique utilizes an innovative chemical fuming process to enhance fingerprints on the above-mentioned surfaces.

Developing fingerprints on metallic objects or on surfaces where the prints have been wiped or washed off with soap water can be carried out by creating a negative image of the print known as an electrochromic image. This method is based on the electrical insulating properties of chemical components of fingerprints that block the electric current. When an electric current is applied to the print, a deposit of colored electro-active film is observed in the bare regions between the fingerprint deposits which are the electrochromic image of the print. This method can be further advanced by adding fluorophore molecules to the film that helps to develop a high-contrast fingerprint image.

Magnetic fingerprinting is a recent development of fingerprint technology that provides a clear and non-contaminated fingerprint impression and carries out effective identification with the help of certain online databases in order to derive reliable source information of the print. This technology is used in personal devices and in buildings residing in restricted areas or in buildings that should have special entry permissions/privileges as a means of security purposes.

Micro-X Ray Fluorescence Technology detects the sweat residues found in fingerprints such as sodium, potassium, chlorine, and other elements and thus facilities the visibility of fingerprints based on their location.

Fingerprint processors and sensors are some of the new advancements in this field. Fingerprint processors process the input data received from the sub-systems on the basis of pre-loaded information stored in their memory. After processing the required input data, the output is set up where the fingerprint is matched or no-match. Fingerprint sensors are utilized by fingerprint recognition systems in order to identify and extract the required features for identification purposes through a fingerprint scan using optical sensors.

Nowadays fingerprint credit cards are used by people to carry out payments where implementation of fingerprint recognition ability of the user is carried out on a plastic card similar to a standard credit card.




Footprint/Footwear and Tyre Impressions

Holography is a laser technique used to record footprints present on carpets where a hologram (laser beam) is used for photography.

The electrostatic technique is another method used for footprint analysis in the case of dusty footprints where these dust particles are lifted onto a black vinyl sheet which is placed over the print to be developed when a high voltage is passed through an aluminum foil that covers the vinyl sheet.

Digtrace software is the first integrated software used to capture 3D images of footwear impressions at the crime scene using a digital camera and also to compare footwear traces digitally. Portable handheld scanners and 3D imaging along with photogrammetry have been utilized by crime scene investigators to capture footwear evidence.

Periphography method is used to document tread patterns in tyres using a periphery camera. This method is mainly used to record curved impressions.

3D optical surface scanning method was employed to document both footwear and tyre impression three-dimensionally in snow surfaces where it delivered higher accuracy of results as compared to conventional casting techniques.

Lip Print Impressions

Digital methods for lip print identification can be carried out using software such as Adobe Photoshop 7 where all features of lip prints were traced and the pattern identification was done on the basis of Suzuki and Tsuchihashi’s classification.

According to recent studies, it was shown that the digital photography method proved to be accurate and reliable for gender determination in lip print analysis as compared to lipstick methods or latent methods for lip print development.

EarPrint Impressions

Nowadays 3D ear recognition systems are used for ear print impression analysis (detection, comparison, and identification) that work based on local shape descriptors and ICP (Iterative Closest Point) which is an algorithm used for 3D model reconstruction of surfaces taken from different scans.

Recent studies have shown that it is possible to extract 3D ear characteristics using 3D ear models that are captured using video sequences.

A new device was developed known as an ear print sampler for recording control ear print samples accurately by the means of a controlled deposition process.

Bite Mark Impressions

Bite mark analyses are now carried out using 3D scanners such as contact and laser scanners where the reconstruction of the geometric shape of the object is done by gathering the geometric information from the surface of that particular object.

In geometric morphometric analysis, the morphological features of an object such as shape and size are defined using landmark points by 3D imaging techniques using specific software.

A new computer-assisted method using Sidexis Next Generation software along with some statistical tests was utilized in bite mark analysis for gender determination.



Conclusion

With increasing crimes and emerging loopholes in conventional practices for detecting impression evidence, the need for effective forensic applications is critical in solving crimes and for identifying individuals of criminal nature.

Sherlock Institute of Forensic Science (SIFS) India provides their best services in fingerprint analysis and they are being the best institute to provide training in different courses in both online and offline mode. You can visit the institute page for more details.