TY - JOUR
T1 - Impact of storage conditions and time on DNA yield from ammunition cartridges
AU - McElhoe, Jennifer
AU - Mandracchia, Therese
AU - Bille, Todd
AU - Holland, Mitchell
N1 - Funding Information:
The authors would like to acknowledge Dr. Craig O’Connor of the Office of Chief Medical Examiner in New York City and Lauren Canale of the California Department of Justice laboratory for their support and input.
Publisher Copyright:
© 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.
PY - 2023/7
Y1 - 2023/7
N2 - Recovery of suitable amounts of DNA from ammunition cartridges for short tandem repeat (STR) or mitochondrial (mt) DNA analysis has been a challenge for crime laboratories. The metal composition of cartridge cases and projectiles exposes the DNA to harmful ions that damage and ultimately degrade the DNA such that it cannot be effectively amplified. The current study assessed the impact of time and storage conditions on touch DNA deposited on cartridge components of varying metal content: aluminum, nickel, brass, and copper. Elevated humidity levels facilitated greater DNA degradation and loss compared to low humidity (or “dry”) conditions, indicating that recovered cartridge component evidence should be stored in a low-humidity environment immediately after collection, preferably with a desiccant. As expected, a relationship was observed between the amount of time elapsed since the cartridge components were handled and the associated DNA yield. Interestingly, while yields dropped considerably in the first 48–96 h post-handling, regardless of the storage conditions, a layering effect was observed that helps maintain a relatively constant level of surface DNA over extended periods of time. An apparent layering effect was also observed on cartridge components following multiple surface depositions, where yields were two times higher than single deposition samples at similar timepoints. Overall, these findings suggest that storage conditions and a layering affect play an important role in the preservation of DNA on ammunition components.
AB - Recovery of suitable amounts of DNA from ammunition cartridges for short tandem repeat (STR) or mitochondrial (mt) DNA analysis has been a challenge for crime laboratories. The metal composition of cartridge cases and projectiles exposes the DNA to harmful ions that damage and ultimately degrade the DNA such that it cannot be effectively amplified. The current study assessed the impact of time and storage conditions on touch DNA deposited on cartridge components of varying metal content: aluminum, nickel, brass, and copper. Elevated humidity levels facilitated greater DNA degradation and loss compared to low humidity (or “dry”) conditions, indicating that recovered cartridge component evidence should be stored in a low-humidity environment immediately after collection, preferably with a desiccant. As expected, a relationship was observed between the amount of time elapsed since the cartridge components were handled and the associated DNA yield. Interestingly, while yields dropped considerably in the first 48–96 h post-handling, regardless of the storage conditions, a layering effect was observed that helps maintain a relatively constant level of surface DNA over extended periods of time. An apparent layering effect was also observed on cartridge components following multiple surface depositions, where yields were two times higher than single deposition samples at similar timepoints. Overall, these findings suggest that storage conditions and a layering affect play an important role in the preservation of DNA on ammunition components.
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U2 - 10.1007/s00414-023-03018-w
DO - 10.1007/s00414-023-03018-w
M3 - Article
C2 - 37237149
AN - SCOPUS:85160401321
SN - 0937-9827
VL - 137
SP - 995
EP - 1006
JO - International Journal of Legal Medicine
JF - International Journal of Legal Medicine
IS - 4
ER -