Effects of chemical and biological warfare agent decontaminants on trace survival: Impact on fingermarks deposited on paper

Chemical and biological events present a challenging environment for forensic scientists to perform their work. This research is the follow-up of the previous article that investigated the impact of decontaminants on fingermarks deposited on glass. In the present study, the focus shifted to paper, a porous and sensitive substrate where fingermark residues are absorbed and cannot be optically seen, making their detection more difficult. Paper is also highly relevant in forensic casework, as demonstrated by the anthrax letter events. Here the impact of 16 decontaminants on fingermarks deposited on paper and on the subsequent development with Ninhydrin, Indanedione-zinc, Physical Developer and Oil Red O was evaluated (by visual examination) by four evaluators. The results of the study demonstrated that the outcome of the development technique is influenced by the persistence of fingermarks compounds targeted by the development technique. As expected, the enhancement and detection methods that target amino acids, that is, Ninhydrin and Indanedione-Zinc had little success when liquid decontaminants were applied to the traces. Although the Physical Developer method revealed more promising results, this technique is generally less reliable compared to others. Therefore, results obtained using this method should be interpreted with greater caution but showed a good chance of success for many decontaminants. Additional tests were conducted using the Oil Red O development technique to evaluate the impact of decontaminants on the lipidic components of fingermarks. Similar to the findings with Physical Developer, the results obtained with Oil Red O showed promising recovery potential and should be further explored.