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

Abstract

An extensive literature review and new post-irradiation experimental results are presented of genotyping blood stains and hair, and physical examinations of latent fingerprints, hairs, and fibers. Results indicate that successful development of nuclear short tandem repeat (STR) and mitochondrial DNA sequence profiles from human blood and hair evidence is possible-up to a point-following exposure to gamma, neutron, beta, and alpha radiation at several levels that would most likely be present at this type of crime scene (i.e., a "dirty bomb," etc.). Commencing at gamma radiation levels between 90 and 900kGy, DNA analysis using conventional DNA techniques was unsuccessful. In general, irradiation negatively affected the quality of latent fingerprints. All four radiation types degraded most fingerprint samples at all doses; nevertheless, many fingerprints remained of value for potential use in comparison. Although variable from one hair to another, microscopic changes observed for all types and levels of irradiation could potentially result in false exclusions. Negligible microscopic changes were observed in papers and fibers (used as substrates for fingerprints and bloodstains) up to 90kGy gamma, but fluorescence of fibers began to change above that dose. Paper and fibers, as well as plastic evidence enclosures, became extremely brittle leading to breakage after a gamma dose of 900kGy.

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

“…2). This result is unusual and not demonstrated by prior studies exploring similar effects [17,18,[38][39][40]42]. It is unlikely that inherent template damage or cellular function is responsible for these observations, since the doses applied are beyond those expected to initiate any adaptive DNA repair response [45][46][47].…”

“…This has also been achieved for dried bloodstains up to 381 90 kGy [40], although reductions in peak height are typical 382 after 10 kGy [17,18,38]. Successful STR genotypes and HV1…”

Blast Suppression Foam, Aqueous Gel Blocks, and their Effect on Subsequent Analysis of Forensic Evidence*

“…The present study examines potential effects on recovery and development of conventional forensic evidence when blast suppression foam and/or an aqueous gel barrier to light shrapnel are used in conjunction with render‐safe procedures. The potential effects of various radiation types on evidence have been addressed elsewhere (3).…”

Forensic determination of hair deposition time in crime scenes using electron paramagnetic resonance

“…This gap in knowledge is unexpected as hair fibers are one of the most common types of trace evidence found at crime scenes because healthy humans lose (on average) 50-150 telogen phase hairs a day [6], pulling hair is relatively easy especially during a struggle [7], and hair is generally very persistent, especially on rough fabrics and beneath fingernails [8]. Hair strands found at a crime scene can provide confirmatory proof to link to a person or animal, provide environmental exposures or drug history of the donor with their extended window of detection compared to blood and urine, and via DNA profiling, identify the source of the evidence (subject and/or species; [9][10][11][12][13][14][15][16][17]). Other advantages of using hair samples include the ability to store samples at room temperature, they are difficult to adulterate, and the non-invasive nature of collecting hair samples compared to blood or urine samples facilitates the process [17,18].…”