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`The Chemistry of Latent Prints from Children and Ad nits
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`Gary Mong, M.S.1
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`Steven Walter, Ph.D.2
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`Robert Ramotowski, M.S.3
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`Tony Cantu, Ph.D.3
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`Introduction
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`There are numerous literature sources that detail the composition of sweat. These studies typically used
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`solvents or absorbent papers/materials to extract sweat samples directly from the skin surface of volunteers.
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`However, these methods may extract different chemical compounds than those that would be deposited by
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`deals in these studies on contained the informatiIn addition, brief contact with a surface (e.g., a latent print).
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`from the sweat gland. This is also not very immediately after being excreted with samples that are collected
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`representative of the fact that most examiners seldom recover fresh prints from the crime scene.
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`There was a need to not only study the chemical compounds present in a deposited latent print, but also
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`examine how these compounds changed with time. The ultimate goal of obtaining this information was to
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`guide future research efforts toward visualizing the more stable compounds ( or even stable breakdown
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`products) that are identified from this work. This would involve possibly developing new visualization
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`methods or modifying existing techniques. Another aspect of this work involved the study of children's
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`prints. Recent work done by Dr. Michelle Buchanan at the Oak Ridge National Laboratory (ORNL), in
`latent
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`cooperation with Mr. Art Bohanan of the Knoxville, TN Police Department, found that children's prints are
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`particularly difficult to recover from surfaces [1,2]. This was especially true in cases involving child
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`abductions, when attempts to process car seats yielded little success beyond a few days for young children's
`prints.
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`Pacific Northwest National Laboratory (PNNL) was recently funded to continue and build upon ORN L's
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`work. PNNL collected and analyzed samples from adults and children and then studied changes that occurred
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`over time. The Savannah River Technical Center (SRTC) also conducted research in this area. The latter
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`work focused on examining the breakdown products of lipid oxidation, and in particular, the formation of
`hydroperoxides.
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`Work Performed by the Pacific Northwest National Laboratory
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`The group at PNNL collected and analyzed samples from approximately eighty-five subjects ranging
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`in age from a young child to a middle-aged adult. The preliminary results indicate that not only do young
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`children leave considerably less residue on a surface (in some cases as little as 1/20 that of adults), the lipid
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`portion of their prints is composed primarily of cholesterol, cholesterol esters, and fatty acids. Most of these
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`compounds breakdown relatively rapidly, except for the saturated fatty acids (e.g., stearic, palmitic).
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`Unfortunately, these saturated compounds are not very chemically reactive.
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`Latent prints were collected from volunteers by having them place sebaceous prints on GFA glass fiber
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`filter papers (Van Waters and Rogers, 4.25 cm circles). With adult samples, extractions were done soon after
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`deposition (as reasonable as possible), and then after 10, 30 and 60 days. With children's prints, extractions
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`1 Pacific Northwest National Laboratory, Richland, WA.
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`2 Savannah River Technical Center, Aiken, SC.
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`3 United States Secret Service, Forensic Services Division, Washington, DC.
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`Volume 37 No. 2
`Reactive Surfaces Ltd. LLP
`Ex. 1022
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`Reactive
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`Lipid Cumposru‘un of Samples from Children
`Freshly Depnslled Prints
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`Lipid Cumpnsiliun ul Samples from Adults
`Freshly Deposited Prints
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`Figure I: The lipid composition (by weight percent) ot‘prints deposited by children (left) and from adults
`(right).
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`were done only after deposition and then after 30 days. The extraction solvent was chloroform. Samples were
`dcrivitized using diazomcthanc.
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`Figure I shows a comparison of recently deposited latent prints from 10 adults and 3 children (aged lO-l 2). The
`most noticeable differences occur with wax esters and cholesterol. The anomaly that occurs with the cholesterol
`peak with children was caused by a group of four females whose prints contained approximately 85-90%
`cholesterol. Due to limitations placed on the use of human subjects as volunteers for this study, the individuals
`could not be re-sampled to verify the observed results. Although children have significantly more cholesterol
`than adults, the average amounts are typically less than ten percent. PNNL is in the process of preparing their
`final report, which will contain detailed information relating to the aging studies.
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`PNNL also performed a squalene aging study. They found that approximately 40% of the squalene residue
`had been converted to other materials within a twenty—day period. Chromatographic peaks were observed before
`and after the parent squalene peak, indicating that products of lower and higher molecular weight were being
`formed. A similar test was performed with oleic acid. After approximately seventeen days, the oleic acid peak
`was virtually gone. The two primary breakdown products were found to be nonanedioic acid and 9—epoxy oleic
`acid.
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`Work Performed by the Savannah River Technical Center (SRTC)
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`The experiments being done at the SRTC involved directly analyzing compounds present in a latent print
`{e.g., squalene) and characterizing their breakdown products. A series of standard lipids representative of the
`various lipid classes found in latent prints were used. These compounds included triglycerides, fatty acids, wax
`esters, cholesterol, cholesterol esters, and a sensitizer (protoporphyrin 1X dimethyl ester, 0.01% of the overall
`mixture). The sensitizer was added to catalyze the reaction between triplet oxygen and light to form singlet
`oxygen (a highly reactive species). A 100 Mg amount of this mixture was placed onto a glass slide and aged in
`various conditions (e.g., light/no light, and/or indoors/outdoors).
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`The oxidation of unsaturated lipids is accelerated by metals, light, heat, and by several initiators and can
`operate through autoxidation or photo—oxidation pathways [3]. The primary autoxidation products are allylic
`hydroperoxidcs. The double bonds present in unsaturated compounds typically remain, but may change position
`and/or configuration. Hydroperoxides may also undergo further changes.
`In some cases, volatile compounds of
`lower molecular weight are formed (e.g., aldehydes) which often cause the familiar odors associated with lipid
`breakdown. However, this is not the dominant process. For example, the thermal decomposition of linoleate
`hydroperoxide at 210°C gives 82% ofthe dimer product and only 4—5% volatile organic compounds. Another
`possibility involves the formation of rearrangement products (with the same chain length) and products of
`further oxidation or of reaction with solvent (or other compounds present). The final pathway involves the
`formation of products of higher molecular weight (e.g., dimers, poiymers). Photo—oxygenation involves
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`interaction between a double bond and the highly reactive species singlet oxygen (produced from ordinary triplet
`oxygen by light in the presence of sensitizers, like chlorophyll, erythrosine, rose bengal, methylene blue, etc.)
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`The SRTC proposed measuring the amount of hydroperoxides present by chemiluminescence.
`Chemiluminescence is produced by the reaction of hydroperoxides and luminol in the presence of cytochrome c.
`Luminescence levels will be measured by adapting a published chemiluminescence assay (using an integrating
`CCD camera) [4].
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`The SRTC (like PNNL) found that unsaturated compounds are depleted rapidly from a latent print deposit,
`even in cool, dark storage conditions. Oxidation, not evaporation, was the primary reason that these unsaturated
`compounds were not detected. Some loss of saturated fatty acids was observed. Samples on glass slides that
`were subjected to outdoor conditions (e.g., rain) lost most of the lipids in the mixtures (with the exception of wax
`esters). Aged lipid samples (approximately five months) formed some polymeric material that adhered to the
`slides. Unlike the original mixture, this material was not soluble in warm diethyl ether.
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`Squalene appears to be the most reactive of the lipids. Squalene exposed to air will begin to oxidize relatively
`quickly and eventually form a waxy solid. One experiment indicated that 98% of a thin film of squalene was lost
`after a four hour exposure to sunlight (a similar loss required four days of exposure to normal room lighting
`conditions). An experiment done in which the UV component of sunlight was filtered from the squalene resulted
`in 57% of the deposit surviving four hours of exposure. Squalene oxidized with ultraviolet radiation (and thus
`forming 1O2) is known to form volatile compounds like acetaldehyde, formaldehyde, acetone, malonaldehyde, and
`6-methyl-5-hepten-2-one [5]. As with other lipids, oxidation is the primary mechanism responsible for squalene’s
`disappearance. When a nitrogen atmosphere is used, 65% of squalene remained after a four hour exposure to
`sunlight.
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`Using another recently published chemiluminesce assay method [6], the SRTC was able to quantify the
`amount of hydroperoxides present in a sample of squalene that had been exposed to a month of direct sunlight.
`The sample was found to have about 0.07r moles of hydroperoxide per mole of squalene. Subsequent testing
`indicates that the hydroperoxide concentration peaks within about two days after exposure to direct sunlight.
`Another experiment found that after one month of exposure, 10% of the squalene residue was composed of
`hydroperoxidcs. In future experiments, additional lipids will be analyzed as well as sebum from latent prints.
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`Conclusion
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`The SRTC data has helped to better understand some of the results observed in the PNNL experiments. The
`results obtained from both projects will provide a better understanding of latent print chemistry involving both
`children and adults. In addition, it is hoped that the aging study data will help direct future research efforts by
`identifying stable compounds that may eventually be visualized physically, chemically, or optically.
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`References
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`[1] Bohanan, A. “Latents from Pre-pubescent Children Versus Latents from Adults," Journal ofForensic Identification, V.
`48, No. 5, 1998, pp. 570-573.
`[2] Buchanan, M.V.; Asano, K.; and Bohanan, A. “Chemical Characterization of Fingerprints from Adults and Children,"
`SPIE Proceedings: Forensic Evidence Analysis and Crime Scene Investigation, V. 2941, 1996, pp. 89-95.
`[3] Gunstone, FD. Fatty Acid and Lipid Chemistry. Chapman & Hall: London, I996.
`[4] Miyazawa, T.; Fujimoto, K.; and Kaneda, T. “Detection of Picomole Levels in Lipid Hydroperoxides by a
`Chemiluminescence Assay,” Agric. Biol. Chem, V. 51, 1987, p. 2569.
`[5] Yeo, H.C.H. and Shibamoto, T. “Formation ofFormaldehyde and Molonaldehyde by Photo-oxidation of Squalene,”
`Lipids, V. 27, No. 1, 1992, p. 50.
`[6] Pinchuk, 1., Schnitzer, E.; and Lichtenberg, D. “Kinetic Analysis of Copper-induced Peroxidation of LDL,” Biochimicu
`et Biophysica Acta, V. 1389, No. 2, 1998, pp. 155-172.
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