Could SecondaryDNATransfer Falsely Place Someone at the Scene of a Crime?^,

Abstract

The occurrence of secondary DNA transfer has been previously established. However, the transfer of DNA through an intermediary has not been revisited with more sensitive current technologies implemented to increase the likelihood of obtaining results from low-template/low-quality samples. This study evaluated whether this increased sensitivity could lead to the detection of interpretable secondary DNA transfer profiles. After two minutes of hand to hand contact, participants immediately handled assigned knives. Swabbings of the knives with detectable amounts of DNA were amplified with the Identifiler(®) Plus Amplification Kit and injected on a 3130xl. DNA typing results indicated that secondary DNA transfer was detected in 85% of the samples. In five samples, the secondary contributor was either the only contributor or the major contributor identified despite never coming into direct contact with the knife. This study demonstrates the risk of assuming that DNA recovered from an object resulted from direct contact.

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

“…Interestingly, studies involving handshaking and handling experiments using these sensitive kits reported similarly varied results. For example, Cale et al [15] found that 17 of 20 knives that yielded quantifiable DNA showed alleles matching those of the handshaker, with these alleles ranging from a minor profile to a major profile in the mixtures obtained. In particular, 25% of the profiles recovered showed a major component matching the profile of the handshaker [15].…”

“…For example, Cale et al [15] found that 17 of 20 knives that yielded quantifiable DNA showed alleles matching those of the handshaker, with these alleles ranging from a minor profile to a major profile in the mixtures obtained. In particular, 25% of the profiles recovered showed a major component matching the profile of the handshaker [15]. Similarly, in a study involving handshaking and then handling of plastic tubes, 20% of the results obtained showed DNA from secondary transfer which exceeded that from primary transfer [16].…”

Intraspecific DNA contamination distorts subtle population structure in a marine fish: Decontamination of herring samples before restriction‐site associated sequencing and its effects on population genetic statistics

“…In addition, special consideration should be given to sampling conditions, such as the bulk collection (Greenstone, Weber, Coudron, & Payton, 2011;King et al, 2011) or storage of specimens that could result in the accidental mixing of bodily fluids or cells. For example, in forensic science, considerable attention has been given to the potential of intraspecific contamination during sample collection (Cale, Earll, Latham, & Bush, 2016) and sample processing in the laboratory (Vandewoestyne et al, 2011), though such practices are less common in molecular ecology.…”

Forensic metrology: its importance and evolution

“…Validity of DNA profiling is generally discussed only in terms of wrong match probability, that is the probability that two individuals share the same DNA components used to profile a single individual. It has been proven [14] that the wrong match probability represents only the definitional uncertainty, and that this contribution might be order of magnitude lower than all other uncertainty contributions that might be originated in the references used in the analysis, as well as in the possible sample contamination, amplified by the DNA amplification methods employed when the available material is not enough to run the test [14,15].…”