Gamma Irradiation as a Biological Decontaminant and Its Effect on Common Fingermark Detection Techniques and DNA Profiling

Abstract

The use of disease-causing organisms and their toxins against the civilian population has defined bioterrorism and opened forensic science up to the challenges of processing contaminated evidence. This study sought to determine the use of gamma irradiation as an effective biological decontaminant and its effect on the recovery of latent fingermarks from both porous and nonporous items. Test items were contaminated with viable spores marked with latent prints and then decontaminated using a cobalt 60 gamma irradiator. Fingermark detection was the focus with standard methods including 1,2-indanedione, ninhydrin, diazafluoren-9-one, and physical developer used during this study. DNA recovery using 20% Chelex extraction and quantitative real-time polymerase chain reaction was also explored. Gamma irradiation proved effective as a bacterial decontaminant with D-values ranging from 458 to 500 Gy for nonporous items and 797-808 Gy for porous ones. The results demonstrated the successful recovery of latent marks and DNA establishing gamma irradiation as a viable decontamination option.

Effects of CBRN Decontaminants in Common use by First Responders on the Recovery of Latent Fingerprints—Assessment of the Loss of Ridge Detail on Glass

“…For example, little is reported about the effect that decontamination procedures that remove and/or neutralize chemical agents have on forensic trace material. This lack of understanding can be partly explained by the fact that most of the research has focused on specific disinfection and sterilization techniques relating to biologically contaminated objects . Other research focused on methods to remove radiological contaminants .…”

Potential effects of ionizing radiation on the evidentiary value of DNA, latent fingerprints, hair, and fibers: A comprehensive review and new results

“…Unfortunately, individual fingerprints were not split into irradiated/untreated halves, so that the ability to draw definitive conclusions is limited. A subsequent study [57] found no adverse effect on recovery of fingerprints on porous and non-porous materials for gamma doses up to 40 kGy (the highest dose tested). One study even showed that, for fingerprints less than 2 weeks old, there was an increase in characteristic points of about 50% after a low (unspecified) gamma dose [75].…”

“…Due to the typeable DNA remaining, both gamma and beta irradiation were judged less effective than ethylene oxide for decontamination. In another decontamination study DNA recovery from blood and paper was approximately 5% after a gamma dose of 5 kGy (no DNA typing was reported) [57]. The range of gamma doses used was nominally 0.5, 1, 2, 3, 5, and 10 kGy.…”

“…In Evans et al [91], evaluation focused on the ability to develop fingerprints either prior to or after deposition of fingerprints and exposures to alpha radiation, rendering results at least somewhat less comparable to this study. Other studies note the effects of a variety of developers on irradiated fingerprints [57,74,77]. In each of these cases, a variety of image quality resulted, but was focused on usability of the print.…”

Degradation of nuclear and mitochondrial DNA after γ-irradiation and its effect on forensic genotyping

“…These lesions can prevent strand uncoiling, alter primer binding sites, and/or block DNA polymerase during PCR [14,15]. This results in allelic dropout, particularly for longer amplicons that incur DNA damage lesions with greater frequency [16], following sufficiently high doses (> 10 kGy) of γ-radiation [17,18]. multiplexed STRs is unrivalled by HVR sequencing [23,24].…”