The Integration of UV/IR Photography into the Processing Sequence of Cyanoacrylate Fumed Semi-Porous Evidence
Abstract: When recovering identifiable friction ridge patterns from semi-porous materials such as retail packaging like cereal boxes, band aid boxes, and other items that have printed multi-colored surfaces on one side, and a paper backing on the other, most default to magnetic powder. Others attempt cyanoacrylate fuming with a dye stain. Unfortunately, the latter can result in the distortion of the pattern by applying a liquid to the substrate, or the actual destruction of the evidence. This article suggests that the integration of a full spectrum camera into the sequence of processing this type of evidence, offers a valuable first look before performing a process that could potentially alter or destroy it.
Introduction: Deciding how to process evidence when looking to retrieve identifiable friction ridge patterns can be difficult at times. However, the philosophy of starting with the least destructive method and working toward the more destructive method can never change. Also, photographing the evidence during each sequence of these steps is paramount in case the next is too destructive. During the research of this project, a collection of forensic practitioners from varying agencies were asked what their “go to method” was for producing identifiable friction ridge patterns when working with semi-porous materials that had a multicolored or patterned background such as; lottery ticket scratch offs, band aid boxes, magazines, or certain retail packaging. The average response of approach method from those solicited were mostly the same with a few different variances. Some stated that they went straight to magnetic powder. Others stated to lightly fume (cyanoacrylate) the item, then use magnetic powder and/ or a combination of fluorescent powder then magnetic powder. There were others that used a method of cyanoacrylate fuming, then dye stained with MBD or Rhodamine 6G applying with a pipette. What was surmised was that after the fuming of the evidence, the first step utilized was to look at the evidence with oblique lighting to try and locate the friction ridge patterns. If patterns were found, they photographed under oblique lighting conditions and then proceeded to the next their next step which was the application of some type of powder or dye stain. As stated before, applying liquid dye stains can alter or destroy the evidence when working with semi-porous substrates. Also, applying a powder, whether it is fluorescent, UV/IR, or magnetic powder can still fill in some of the third level detail such as pores and edge shapes. The author suggests the integration of photographing the evidence with a full spectrum camera utilizing its ultra violet and infrared capabilities before these potentially destructive steps.
Materials and Methods: Multiple fingers were rubbed on the forehead to apply a matrix of sebaceous oils. Multiple friction ridge patterns were deposited on the following: Band Aid box, dyranex ear loop mask box, Sealguard evidence tape box, Toshiba hard drive retail packaging, and a magazine cover. The patterns that were deposited were intentionally applied to areas that had multiple colored or patterned backgrounds. These items were chosen because if one were to apply a liquid dye stain, especially if it required a rinse, it would result in distortion or destruction of the item. All items were then fumed via the cyanoacrylate fuming method, in a Misonix automated fuming chamber, with a twenty-minute fume time and ten-minute purge cycle. The items were then removed from the chamber and viewed with a white light at oblique angles to locate potential evidence of friction ridge patterns. Once located, the patterns were photographed under normal light conditions, and again with oblique lighting. The recovered patterns were then photographed using a 403nm filter and a handheld UV Light (365nm). Magnetic powder was then applied to those same patterns and again photographed under normal light conditions. The patterns that now had magnetic powder applied were then photographed with an 830nm filter, and fluorescent LED lighting from the ceiling of the lab. List of equipment used:
Fuji X-T1 UV/IR Mirrorless Full Spectrum Camera
Fuji Fujifilm XF 60mm f2.4 Fujinon Macro ASPH Super EBC Lens
B+W 39mm 403nm ultraviolet filter
B+W 39mm 830nm infrared filter
Misonix CA-3000 cyanoacrylate fuming chamber
UVFT100A ForensiTORCH from the megaMAXX 3-Watt Alternate Light System
Streamlight Stylus Pro (handheld white LED flashlight)
Magnetic Fingerprint Powder – Sirchie (Regular Black)
Note: Due to the hot spot in the center of the photographs that is a common and normal occurrence using the UV and IR filters with this lens, the photographs in this study show the friction ridge pattern offset from the center.
Results:
In Figure 1(b), the viewer can see that the best oblique lighting achieved was minimal for this particular item. However, in Figure 1(c), when next photographed using the 403nm UV filter and a handheld UV light (365nm), level 3 details are now observed (e.g., pores, incipient ridges). In Figure 1(d), after magnetic powder has been applied, most but not all of the pores and some of the ridge shapes that were clear, are now filled in by the powder. In Figure 1(e), the item is now photographed with the 830nm filter, and fluorescent lighting from the ceiling of the lab. While the ridge detail in Figure 1(d) was readily observable, the detractions from the background have been significantly reduced.
Figure 1
After fuming, the items were viewed via (a) normal lighting conditions, (b) oblique lighting, (c) a 403nm filter with 365nm UV lighting, (d) magnetic powder, (e) and finally with an 830nm filter with fluorescent lighting.
The same results can be seen in Figure 2(c) when using the 403nm filter and a handheld UV light (365nm). Once again, level 3 details are observed, but now the white background in the center of the pattern is does not create enough contrast for the observation of the ridge characteristics. In Figure 2(d), this is resolved with the 830nm filter, and fluorescent lighting. Almost all background detractions are now gone.
Figure 2
After fuming, the items were viewed via (a) normal lighting conditions, (b) oblique lighting, (c) a 403nm filter with 365nm UV lighting, (d) magnetic powder, (e) and finally with an 830nm filter with fluorescent lighting.
Once again, the white background in Figure 3(b) and Figure 3(c) result in the friction ridges not being able to be observed; however, once the magnetic powder is applied, they are. There is no great difference between Figure 3(d) and Figure 3(e), but Figure 3(d) with just magnetic powder seems to offer more detail.
Figure 3
After fuming, the items were viewed via (a) normal lighting conditions, (b) oblique lighting, (c) a 403nm filter with 365nm UV lighting, (d) magnetic powder, (e) and finally with an 830nm filter with fluorescent lighting.
The black ink used on the Sealguard evidence tape box (Figures 4(a) – Figure 4(d) is an example of how certain inks are not mitigated as easily as other inks. Figure 4(d), again with only magnetic powder applied, the most detail observed.
Figure 4
After fuming, the items were viewed via (a) normal lighting conditions, (b) oblique lighting, (c) a 403nm filter with 365nm UV lighting, (d) magnetic powder, (e) and finally with an 830nm filter with fluorescent lighting.
An example of how certain inks in packaging that work better with the 403nm filter and a handheld UV light (365nm) is Figure 5(c). The closest runner up in this series is Figure 5(b) where only oblique lighting is used.
Figure 5
After fuming, the items were viewed via (a) normal lighting conditions, (b) oblique lighting, (c) a 403nm filter with 365nm UV lighting, (d) magnetic powder, (e) and finally with an 830nm filter with fluorescent lighting.
The magazine (Figures 6(a) – 6(e)) also had the best results with the 403nm filter and a handheld UV light (365nm) as evidence in Figure 6(c). In Figure 6(b), oblique lighting did not show anything. The light had to be angled almost 90 degrees to the substrate to use the reflection from the gloss of the cover to create a contrast that could render visible friction ridges. In Figure 6(d), the magnetic powder was barely visible and it completely disappeared Figure 6(e).
Figure 6
After fuming, the items were viewed via (a) normal lighting conditions, (b) lighting angled at almost 90 degrees, (c) a 403nm filter with 365nm UV lighting, (d) magnetic powder, (e) and finally with an 830nm filter with fluorescent lighting.
Discussion and Conclusion:
The results show that with any piece of evidence, there are going to be multiple variables. The different colored or patterned backgrounds are made out of different materials. Products that are printed vary, and different types of inks are used that respond differently with a UV filter, and then differently with an infrared filter. Sometimes neither the UV filter, nor the infrared filter, perform; and something as simple as magnetic powder works best. But if you are left with just the magnetic powder, after photographing, your next step is to lift the friction ridge pattern. If tape is used, that could present problems such as bubbles, creases, and pulling part of the substrate off. Integrating the use of a full spectrum camera with UV/IR capabilities into the everyday sequence of processing semi-porous materials should be compulsory if the equipment is available. Photographing each step taken during processing should already be common practice or protocol. The time taken when changing the lighting conditions and filters is negligible when compared to the results. It is a non-invasive step that should not be bypassed if the equipment is readily accessible. Applying these small extra steps could aid in the recovery of far more identifiable friction ridge patterns.
For further information, please contact:
Frederick D. Zigan
Roswell, GA 30075
evidence@BigfootForensics.com
References:
Richards, A.; Leintz, R. “Longwave UV Imaging,” Evidence Technology Magazine. Vol. 10, No. 4, July-August 2012, http://www.ultravioletcameras.com/pdf/ETM-LongwaveUV.pdf (Accessed May 14, 2020).
Foster+Freeman “DCS5 applications: Infrared & Longwave Reflected UV Imaging of ‘superglue’ fumed evidence” Application Note, Issue 1, May 2017, http://www.fosterfreeman.com/download_application_notes/DCS5-Reflected-IR-UV.pdf (Accessed May 14, 2020)