Shedding light on the relative DNA contribution of two persons handling the same object

Oldoni, Fabio; Castella, Vincent; Hall, Diana

doi:10.1016/j.fsigen.2016.07.002

Cited by 62 publications

(52 citation statements)

References 43 publications

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“…There is interest in whether the timing or order of individuals handling an object can be inferred from the touch DNA evidence; for example, it was previously believed that the major contributor will be the person who handled the item most recently as their DNA would displace or overwhelm prior depositions [1]. While this holds a logical appeal and overall this pattern can be observed in the data on the subject [45,55], exceptions arise and broad conclusions about activity or handling order could be erroneous [56] as there is wide variability. There are instances of the most recent handler's DNA or even the DNA of the depositing hand being absent or only present as a partial minor contributor [57,47].…”

Section: Persistence and Interactions Of Trace Dna In Its Environmentmentioning

confidence: 99%

A review of trace “Touch DNA” deposits: Variability factors and an exploration of cellular composition

Burrill

Daniel

Frascione

2019

Forensic Science International: Genetics

128

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Section: Persistence and Interactions Of Trace Dna In Its Environmentmentioning

confidence: 99%

A review of trace “Touch DNA” deposits: Variability factors and an exploration of cellular composition

Burrill

Daniel

Frascione

2019

Forensic Science International: Genetics

128

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“…Detection of indirectly-transferred unknown DNA alongside expected DNA from the donor has been repeatedly reported, commonly at ≤10% of the profiles obtained, by studies involving handling or wearing of items and DNA profiling using the more sensitive kits [4,10,11,15,16,[25][26][27][28]. It is proposed that hands acquire such nondonor DNA via everyday activities that involve touching other people and other items that have been previously handled [10,16,20,27,28].…”

Section: Detection Of Indirectly-transferred Unknown Dnamentioning

confidence: 99%

“…More recently, indirectlytransferred DNA has been observed in mock social settings [4] and stabbing simulations [5], and has been a key consideration in several high profile criminal cases, such as R v Reed & Reed [6], Fitzgerald v The Queen [7] and the miscarriages of justice of Amanda Knox and Raffaele Sollecito [8]. Furthermore, given that DNA can persist on surfaces for a number of days or weeks depending on the environmental conditions [9] and on objects after use by a subsequent person [10][11][12], persistence of both directly and indirectly transferred DNA also needs to be considered in the evaluation of trace DNA in casework.…”

Section: Introductionmentioning

confidence: 99%

Trace DNA evidence dynamics: An investigation into the deposition and persistence of directly- and indirectly-transferred DNA on regularly-used knives

Meakin¹,

Butcher²,

Oorschot

et al. 2017

Forensic Science International: Genetics

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Empirical data on the transfer and persistence of trace DNA are crucial to the evaluation of forensic DNA evidence. This evaluation can be complicated by the occurrence of indirect DNA transfer; the possibility of which is well established, but research into such transfer is often focussed on unrealistic situations, e.g. handling of DNA-free items after participants have shaken hands for 1-2min. To simulate more realistic scenarios, this study investigated the deposition and persistence of both directly- and indirectly-transferred DNA on knives that had been artificially set up as 'regularly-used'. Each knife was handled in a prescribed manner by a specific participant over two consecutive days to simulate regular use. Each participant then shook hands for 10s with a fellow volunteer and immediately stabbed one of their knives into a foam block repeatedly for 60s. DNA was recovered by mini-taping from triplicate sets of knife handles from four pairings of volunteers after regular use, and at one hour, one day and one week after the handshaking and stabbing events. Total amounts of DNA recovered from the knives, regularly used by a single person, varied among individuals; one volunteer consistently deposited significantly greater amounts than the others, whilst another volunteer did not always leave complete profiles. DNA attributed to the regular user persisted for at least a week, declining with increasing time between DNA deposition and recovery. Non-donor DNA was co-deposited at <5% of the profiles recovered, except for one volunteer, who consistently left DNA from their romantic partner on their knives at ∼25% and ∼11% of the profiles before and after the handshaking and stabbing events, respectively. In three pairings of volunteers, after the handshaking and stabbing events, alleles that could be attributed to the respective handshakers' profiles were detected as partial minor profiles, equating to ∼10% of the profiles recovered. For the fourth pairing of volunteers, only complete single-source DNA profiles matching the regular user's profile were recovered. However, it is important to note that, when indirectly-transferred handshaker DNA was detected, it declined with increasing time between DNA deposition and recovery. These data provide an initial insight into the detection and persistence of directly- and indirectly-transferred DNA that extend the data already available on forensic DNA transfer. The results herein suggest that the sooner an item is sampled after an offence has occurred, the greater the chance of recovering indirectly-transferred DNA, which has implications for forensic reconstructions.

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“…The amount of DNA contributed by individuals to forensic DNA mixture samples is known to vary by individual [1,2]. Estimates of how much DNA an individual contributed to a mixture can provide useful inferences such as subject approximate touch order, relative time handling an object, and the quantity of DNA that can be explained by known reference profiles [1].…”

Section: Introductionmentioning

confidence: 99%

Estimating Individual Contributions to Complex DNA SNP Mixtures

Ricke

Fremont-Smith

Watkins

et al. 2018

Preprint

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A B S T R A C T Mixture analysis and deconvolution methods can identify both known and unknown individuals contributing to DNA mixtures. These methods may not identify all DNA contributors with the remaining fraction of the mixture being contributed by one or more unknown individuals. The proportion of DNA contributed by individuals to a forensic sample can be estimated using their quantified mixture alleles. For short tandem repeats (STRs), methods to estimate individual contribution concentrations compare capillary electrophoresis peak heights and or peak areas within a mixture. For single nucleotide polymorphisms (SNPs), the major:minor allele ratios or counts, unique to each contributor, can be compared to estimate contributor proportion within the mixture. This article introduces three approaches (mean, median, and slope methods) for estimating individual DNA contributions to forensic mixtures for high throughput sequencing (HTS)/massively parallel sequencing (MPS) SNP panels.

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Shedding light on the relative DNA contribution of two persons handling the same object

Cited by 62 publications

References 43 publications

A review of trace “Touch DNA” deposits: Variability factors and an exploration of cellular composition

A review of trace “Touch DNA” deposits: Variability factors and an exploration of cellular composition

Trace DNA evidence dynamics: An investigation into the deposition and persistence of directly- and indirectly-transferred DNA on regularly-used knives

Estimating Individual Contributions to Complex DNA SNP Mixtures

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