Effect of Dactyloscopic Powders on DNA Profiling From Enhanced Fingerprints

Abstract

We conducted a study on the effect of fingerprint enhancement methods on subsequent short tandem repeat profiling. First, we performed a study typing blood traces deposited on 5 different surfaces, treated with 8 types of dactyloscopic powders. Three different DNA extraction methods were used. Subsequently, we analyzed latent fingerprints on the same 5 surfaces enhanced with the 8 different powders used in the first part of the study. This study has demonstrated that DNA profiling can be performed on fingerprints left on different substrates, and the substrate will affect the amount of DNA that can be recovered for DNA typing. In the first phase of the study, a profile was obtained in 92% of the 120 samples analyzed; in the second part, in 55% of the 80 samples analyzed, we obtained a profile complete in 32.5% of the cases. From the results obtained, it seems that the powders used in latent fingerprints enhancement, rather than having a direct inhibitory effect on extraction and amplification of DNA, may cause partial degradation of DNA, reducing the efficiency of amplification reaction. It should not be forgotten that these results were obtained under laboratory conditions, and in real caseworks, there may still be different problems involved.

New incompatibilities uncovered using the Promega DNA IQ™ chemistry

“…Importantly, these two groups did not use the newly formulated STR amplification kits more tolerant to PCR inhibition. DNA degradation was also invoked as a potential effect of "magnetic powder" [23] but this effect was not observed in the study presented herein.…”

The effect of mark enhancement techniques on the presumptive and confirmatory tests for blood

“…With fingermarks enhancement, several studies [49][50][51][52][53][54] have shown that most of the reagents commonly used to develop latent marks, such as aluminium powder, black magnetic powder, fluorescent powders, wet powder suspension and 1,2-indanedione do not affect subsequent recovery of DNA. Other specific chemicals such as cyanoacrylate and ninhydrin may have a negative impact on the process as they can either degrade or sequester the DNA or inhibit the PCR reaction [55,56].…”

Evaluation of DNA Extraction Methods for Processing Fingerprint Powder‐Coated Forensic Evidence

“…The effect of fingerprint powders on subsequent DNA analysis has been well documented over the last 15 years . The majority of studies have looked at the impact of fingerprint powders on subsequent DNA analysis, with a focus on: the effect of various substrates ; the quality of fingerprints ; the effect of time ; the effect of materials routinely used in forensic investigations ; and various fingerprint treatments .…”

“…There are only a few studies published comparing multiple DNA extraction techniques for various types of fingerprint powder . Lin et al .…”

“…The DNA IQ™ extraction methodology showed the greatest extraction efficiency in comparison to the Investigator ® protocols, with magnetic fingerprint powders having the largest adverse effect on DNA recovery. A study by Tozzo et al evaluated eight different fingerprint powders and three DNA extraction methods; Chelex, the ChargeSwitch Forensic DNA Purification Kit and the QIAGEN QIAamp ® DNA Micro Kits and found the QIAamp ® DNA Micro kit produced the highest percentage of DNA profiles with at least 6 loci successfully amplified.…”