Storability of porcine blood in forensics: How far should we go?

Sparer, Andreas; Serp, Bianca; Schwarz, Lukas; Windberger, Ursula

doi:10.1016/j.forsciint.2020.110268

“…Our meta-analysis suggests near uniformity in effect sizes related to the class of biomolecule studied, analytical technique used to measure degradation, the temperature the bloodstain was aged in, and the type of blood source used. While differences exist in the molecular properties of mammalian blood sources (Windberger et al, 2003;Kim et al, 2016;Kapusta et al, 2017;Windberger, 2019;Sparer et al, 2020;Ecker et al, 2021;Farré et al, 2021), the findings of our meta-analysis suggest that they share similar timewise physicochemical degradation pathways of the biomolecules. This leads to a first key takeaway: most readily available mammal blood sources can be used as a human blood substitute in proof-of-concept TSD studies.…”

Section: Subgroup Analysesmentioning

confidence: 46%

“…This leads to a first key takeaway: most readily available mammal blood sources can be used as a human blood substitute in proof-of-concept TSD studies. Moreover, addition of anticoagulants allows for important experimental flexibility, mirrors human properties (Sparer et al, 2020;Orr et al, 2021) and in at least one TSD study, had minimal effect on the recorded metrics ( (Elliott et al, 2022) but see (Bergmann et al, 2021)). While a variety of suitable mammal alternatives exist (Windberger et al, 2003;Ecker et al, 2021;Orr et al, 2021) and would facilitate expanded TSD research, we still recommend that for integration into forensic casework, experimentation with human blood will be required for validation.…”

Section: Subgroup Analysesmentioning

confidence: 99%

The crux of time: A meta-analysis of ex vivo whole blood degradation

Elliott

¹

,

Shafer²,

Stotesbury³

2022

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Estimating the time since deposition (TSD) of a bloodstain can provide important medico-legal information for crime scene investigation. Research in this area primarily investigates the degradation of either hemoglobin or genetic material over time. In this work, we present a comprehensive meta-analysis on bloodstain TSD research. Our results are interpreted from 25 quantitative studies used to probe the effect of biomolecule studied, analytical technique used, substrate porosity, environmental conditions, and blood source on TSD estimates. There was an overall strong effect of time across studies (Fisher’s Zr = 1.66, r = 0.93), and generally, we found that the type of biomolecule studied (e.g., hemoglobin, DNA) had equal effect sizes for TSD estimation. Differences in the mean TSD effect size were also observed between substrate porosity. Interestingly, the blood source does not significantly influence the magnitude of the effect sizes in TSD estimation. Despite the clear effect of time, forensically relevant prediction of bloodstain TSD remains complicated by inter-donor variability, type of substrate and environmental conditions. We recommend that future bloodstain TSD research increase sample size, include summary statistics and standardize experimental methodologies so that we can develop a quantitative understanding of the physicochemical processes involved in whole blood degradation in ex vivo conditions.

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“…Our meta-analysis suggests near uniformity in effect sizes related to the class of biomolecule studied, analytical technique used to measure degradation, the temperature the bloodstain was aged in, and the type of blood source used. While differences exist in the molecular properties of mammalian blood sources [99][100][101][102][103][104][105] , the findings of our meta-analysis suggest that they do not appear to hamper the timewise physicochemical degradation pathways of the biomolecules. This leads to a first key takeaway: most readily available mammal blood sources can be used as a human blood substitute in proof-of-concept TSD studies.…”

Section: Discussionmentioning

confidence: 99%

The crux of time: A meta-analysis of ex vivo whole blood degradation

Elliott

¹

,

Shafer

²

,

Stotesbury

³

2022

Preprint

0

View full text Add to dashboard Cite

Estimating the time since deposition (TSD) of a bloodstain can provide important medico-legal information for crime scene investigation. Research in this area primarily investigates the degradation of either hemoglobin or genetic material over time. In this work, we present a comprehensive meta-analysis on bloodstain TSD research. Our results are interpreted from 25 quantitative studies used to probe the effect of biomolecule studied, analytical technique used, substrate porosity, environmental conditions, and blood source on TSD estimates. There was an overall strong effect of time across studies (Fisher’s Zr = 1.66, r = 0.93), and generally, we found that the type of biomolecule studied (e.g., hemoglobin, DNA) had equal effect sizes for TSD estimation. Differences in the mean TSD effect size were also observed between substrate porosity. Interestingly, the blood source does not significantly influence the magnitude of the effect sizes in TSD estimation. Despite the clear effect of time, forensically relevant prediction of bloodstain TSD remains complicated by inter-donor variability, type of substrate and environmental conditions. We recommend that future bloodstain TSD research increase sample size, include summary statistics and standardize experimental methodologies so that we can develop a quantitative understanding of the physicochemical processes involved in whole blood degradation in ex vivo conditions.

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“…The blood was placed on ice for transportation back to the laboratory (~15 minutes). Whole mammalian blood with the inclusion of ACD-A is an appropriate substitute for studies of this nature [23][24][25] as bovine blood exhibits similar fluid properties to that of humans [26]. We compared the DNA transfer concentrations, with and without ACD-A using a Twosample T-test, to test for an effect.…”

Section: Sample Preparationmentioning

confidence: 99%

Secondary DNA transfer on denim using a human blood analogue

Ridings

¹

,

Gabriel

²

,

Elliott

³

et al. 2021

Preprint

0

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DNA quantification technology has increased in accuracy and sensitivity, now allowing for detection and profiling of trace DNA. Secondary DNA transfer occurs when DNA is deposited via an intermediary source (e.g. clothing, tools, utensils). Multiple courtrooms have now seen secondary transfer introduced as an explanation for DNA being present at a crime scene, but sparse experimental studies mean expert opinions are often limited. Here, we used bovine blood and indigo denim substrates to quantify the amount of secondary DNA transfer and quality of STRs under three different physical contact scenarios: passive, pressure, and friction. We showed that the DNA transfer was highest under a friction scenario, followed by pressure and passive treatments. The STR profiles showed a similar, albeit less pronounced trend, with correctly scored alleles and genotype completeness being highest under a friction scenario, followed by pressure and passive. DNA on the primary substrate showed a decrease in concentration and genotype completeness both immediately and at 24 hours, suggestive of a loss of DNA during the primary transfer. The majority of secondary transfer samples amplified less than 50% of STR loci regardless of contact type. This study showed that while DNA transfer is common between denim, this is not manifested in full STR profiles. We discuss the possible technical solutions to partial profiles from trace DNA, and more broadly the ubiquity of secondary DNA transfer.

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Storability of porcine blood in forensics: How far should we go?

Cited by 12 publications

References 37 publications

The crux of time: A meta-analysis of ex vivo whole blood degradation

The crux of time: A meta-analysis of ex vivo whole blood degradation

The crux of time: A meta-analysis of ex vivo whole blood degradation

Secondary DNA transfer on denim using a human blood analogue

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