We know that physical evidence found at the crime scene might get contaminated, transition from fresh to old, lose chemical and/or physical characteristics, and might be difficult to recognize after some span of time if unattended. Likewise, fingermarks-patent or latent, can grow old and lose some identifiable features. It is important to know about the aging of fingermark evidence because fingerprint or ridge pattern analysis is majorly subjective. There are only a few aspects that use objective scientific principles and methods to arrive at a conclusion. Unfortunately, the aging of fingermarks cannot be accurately determined using any technology yet and hence relies on ACE-V (Analysis, Comparison, Evaluation, and Verification) method and subjectivity. Ridge pattern analysts often face difficulty explaining how a suspected fingermark fits into the timeframe of the crime. Offering concrete testimony is somewhat affected due to the lack of research and proper methodologies for determining the age of fingermarks.
Both physical and chemical properties of fingermarks are influenced by the passage of time and donor type, environmental conditions, and/or substrates of deposition. Fingermarks are deposited on surfaces, and they are majorly divided into three types: porous, semi-porous, and non-porous.[1] Porous surfaces are wood, sponge, or paper. Examples of non-porous surfaces are glass, plastic and metallic surfaces. Porous surfaces preserve fingermark residue better than non-porous surfaces. In porous substrates, the residue of fingermarks is absorbed into the substrates and hence is protected from the environment. Non-porous substrates do not absorb fingermark residue and hence the fingermarks are exposed to the environment and vulnerable to degradation.[2] Chadwick et al. found out that the number of fingermarks detected on porous substrates was more than on the non-porous substrates [8]. Among non-porous substrates, plastic shows more fingermark degrading signs than glass does with the passage of time.[7]
Studies on the effects of nicotine and its products, prescribed medicinal drugs, cosmetics, and caffeinated products have also been performed. Cosmetic products like face creams and skin moisturizers have been found to make fingerprints more persistent on object surfaces and thus decelerate the rate of degradation.[4] Skin diseases like dermatitis and acne will be a contributing factor toward the changing lipid composition and hence influence the fingerprint quality.[14, 15] Illicit substances such as ammonium nitrate(explosive component) and drugs like powder cocaine and ecstasy have been detected using infrared spectral imaging and Raman spectroscopy.[16,17]
The nature of donors has important parameters like age, sex, BMI, and occupation among others. A study by Czech et al. determined that people with normal BMI have narrower ridge widths than overweight or underweight individuals. [3] The ridge width of women is 11% wider than in women whereas the fingermarks from males have more sebum and sweat content and hence are more durable over time. [3,4] age plays a crucial role in fingermark analysis since the fingermarks of children contain more volatile compounds than adults. Hence the fingermarks of the latter are retained longer in the substrates than those belonging to children. [5,6]
Environmental conditions such as humidity, temperature, and natural light exposure are the most common and are taken into consideration. In a study by De Alcaraz-Fossoul et al., it was found that the presence or absence of natural light was a secondary factor in the decrease of ridge width over time.[7] Another experimental study has concluded that solar radiation may be one of the least influential environmental factors with respect to fingermark degradation.[9] Temperature is a less-studied environmental condition and might be somewhat related to natural light. On the polyvinyl difluoride membrane, relevant changes in the squalene and cholesterol levels were not observed in the temperature range of -200C to 600C. However, the reduction in levels was evident at 1000C. No related physical ridge/fingermark changes 1 were reported.[10] Humidity has been studied with respect to fingerprint development and enhancement methods but is not directly related to degradation patterns. For instance, a study found that the silver nitrate development method is adversely affected by high humidity levels.[11]
The nature of the fingerprints is another contributing factor toward the degradation of ridge details and characteristics. There are two major categories of latent fingerprints: eccrine-rich and sebaceous-rich. Eccrine-rich fingerprints are those that are formed of sweat as the major component and sebaceous-rich fingerprints are formed from oils after touching sebaceous regions in the body like the nose, behind the ears, or forehead. Studies have shown that sebaceous-rich ridge impressions are more persistent on surfaces than eccrine-rich fingerprints due to the evaporation of water from the latter’s residue.[9, 18]
Above mentioned are some factors that affect fingermark deposition and may contribute to their degradation over time. It is important to look what are the common degrading patterns found in such evidence. Ridge discontinuities, changes in ridge width, and loss of viable minutiae were found in various studies involving fingermark degradation with various factors.
Ridge discontinuities are the interruptions occurring in the ridges during the aging process of fingerprints and they appear naturally. These are visible when the fingermarks are enhanced and developed. One of the reasons might be the chemical degradation of the substances present in fingermark residue. With time, the number of discontinuities increases and compromises the integrity and flow of ridges.[1]
More decrease in ridge width was observed in fingermarks deposited on plastic than on glass.[7] In a study by Kapoor and Badiye et al. the fingerprints submerged in water for longer periods (48 hours and 120 hours) showed significant patterns of degradation. Although water played a role, time was a dominant factor too.[12] Loss of height is another degradation pattern observed in fingermarks over time and the changes can be detected under an Optical Profilometer using 3D imaging.[13]
Hence, more research in the area of changes in ridge morphology and characteristics will provide us with in-depth knowledge of fingermark degradation patterns and can help find objective analytical tools which will be reliable and valid to be used in crime scenes and decrease the subjectivity of testimonies in courtrooms.
REFERENCES:
[1] De Alcaraz-Fossoul, J. (Ed.). (2021). Technologies for fingermark age estimations. Springer.
[2] Girod, A., Ramotowski, R., & Weyermann, C. (2012). Composition of fingermark residue: a qualitative and quantitative review. Forensic Science International, 223(1–3), 10–24. https://doi-org.unh-proxy01.newhaven.edu/10.1016/j.forsciint.2012.05.018
[3] Czech, A., Szabelak, A., & Sowiński, A. (2019). Changes in Fingerprints Depending on Physiological Factors. Journal of Forensic Sciences, 64(3), 711–716. https://doi-org.unh-proxy01.newhaven.edu/10.1111/1556-4029.13937
[4] Pleik S, Spengler B, Schäfer T, Urbach D, Luhn S, Kirsch D(2016). Fatty acid structure and degradation analysis in fingerprint residues. Journal of the American Society for Mass Spectrometry Vol.27
[5] Williams DK, Brown CJ, Bruker J. Characterization of children’s latent fingerprint residues by infrared microspectroscopy: forensic implications. Forensic Sci Int. 2011 Mar 20;206(1-3):161-5. doi: 10.1016/j.forsciint.2010.07.033. Epub 2011 Feb 4. PMID: 21295928.
[6] M.V. Buchanan, K. Asano, A. Bohanon, Chemical characterization of fingerprints from adults and children, in: Forensic Evidence Analysis and Crime Scene Investigation, SPIE (International Society for Optical Engineering), vol. 2941, 1996, 89–95.
[7] De Alcaraz, F. J., Barrot Feixat, C., C. Zapico, S., McGarr, L., Carreras, M. C., Tasker, J., & Gené Badia, M. (2019). Latent Fingermark Aging Patterns (Part IV): Ridge Width as One Indicator of Degradation. Journal of Forensic Sciences, 64(4), 1057–1066. https://doi-org.unh-proxy01.newhaven.edu/10.1111/1556-4029.14018
[8] Chadwick, S., Moret, S., Jayashanka, N., Lennard, C., Spindler, X., & Roux, C. (2018). Investigation of some of the factors influencing fingermark detection. Forensic Science International, 289, 381–389. https://doi-org.unh-proxy01.newhaven.edu/10.1016/j.forsciint.2018.06.014
[9] De Alcaraz-Fossoul, J., Patris, C. M., Muntaner, A. B., Feixat, C. B., & Badia, M. G. (2013). Determination of Latent Fingerprint Degradation Patterns – A Real Fieldwork Study. International Journal of Legal Medicine, 127(4), 857–870.
[10] Kim Y et al., 2020. Effect of temperature and exposure time on the stability of cholesterol and squalene in latent fingermarks deposited on PVDF membrane, Journal of Forensic Sciences Vol. 65
[11]Cuthbertson F, Morris JR(1972).The chemistry of fingerprints, Memorandum332, United Kingdom Atomic Energy Authority, Atomic Weapons Research Establishment (AWRE), SSCD
[12] Kapoor N, Badiye A et al(2019). Development of submerged and successive latent fingerprints: a comparative study. Egyptian Journal of Forensic Sciences Vol. 9
[13] De Alcaraz-Fossoul J et al(2019). Application of 3D imaging technology to latent fingermark aging studies. Journal of Forensic Sciences Vol. 64
[14] Saint-Leger D, Bague A, Cohen E, Chivot M. A possible role for squalene in the pathogenesis of acne. I. In vitro study of squalene oxidation. Br J Dermatol. 1986 May;114(5):535-42. doi: 10.1111/j.1365-2133.1986.tb04060.x. PMID: 2941049.
[15] ] Pappas A, Johnsen S, Liu JC, Eisinger M. Sebum analysis of individuals with and without acne. Dermatoendocrinol. 2009 May;1(3):157-61. doi: 10.4161/derm.1.3.8473. PMID: 20436883; PMCID: PMC2835908.
[16] Ng, P. H. R., Walker, S., Tahtouh, M., & Reedy, B. (2009). Detection of illicit substances in fingerprints by infrared spectral imaging. Analytical & Bioanalytical Chemistry, 394(8), 2039–2048. https://doi-org.unh-proxy01.newhaven.edu/10.1007/s00216-009-2806-9
[17] Clemons, K., Wiley, R., Waverka, K., Fox, J., Dziekonski, E., & Verbeck, G. F. (2013). Direct Analyte-Probed Nanoextraction Coupled to Nanospray Ionization-Mass Spectrometry of Drug Residues from Latent Fingerprints Direct Analyte-Probed Nanoextraction Coupled to Nanospray Ionization-Mass Spectrometry of Drug Residues from Latent Fingerprints. Journal of Forensic Sciences, 58(4), 875–880. https://doi-org.unh-proxy01.newhaven.edu/10.1111/1556-4029.12141
[18] De Alcaraz, F. J., Zapico, S. C., Dean, E. R., Mueller, K. E., Johnson, C., & Roberts, K. A. (2021). Evaluation of latent fingermark color contrast as aging parameter under different environmental conditions: A preliminary study. Journal of Forensic Sciences, 66(2), 719–736. https://doi-org.unh-proxy01.newhaven.edu/10.1111/1556-4029.14635
Authored By
Riddhi Roy is a second-year student of Master of Science in Forensic Technology at the University of New Haven, Connecticut, USA. She has pursued her undergraduate degree from the Government Institute of Forensic Science, Nagpur, India. Riddhi has currently completed her Master’s research project in fingermark degradation over time and studied the influence of substrates and temperatures during the degradation process by 2D and 3D analysis. Her paper has been accepted for presentation at the American Academy of Forensic Sciences Annual Conference which is to be held in Orlando, Florida next year.
