DNA profiling of saliva traces habitually deposited on various documents: a pilot study

Abstract

Background: A study was conducted to determine whether the habitualness among individuals to apply saliva to their fingertips (for moistening) while shuffling through pages of a document can provide evidence in cases pertaining to handling of documents in forensic investigations. It involved 200 volunteers, 50% of which were male and 50% were female. The volunteers shuffled the pages of the three substrates (registers, books and magazines). An attempt was made to detect the transfer of saliva onto the substrate while shuffling and generation of DNA profiles from the transferred saliva. The presence of salivary stains was confirmed using iodine fuming test and starch iodine test. Afterwards, the DNA was recovered with substrate cutting method, extracted using QIAGEN® QIAmp DNA mini kit and amplified using the Power Plex® 21 System Kit. Results: The results revealed that 83% of individuals applied saliva onto the documents and majority of females applied saliva. DNA could be successfully recovered from the stains detected on the three substrates, and complete STR profiles could be generated. Main finding: A conclusion can be drawn out that majority of subjects under study were in habit of using saliva to turn pages, and this can be an important evidence to help criminal justice system as DNA profiles could be developed successfully from the substrates. This can be a very good evidence in respect of identifying the individual(s) who handled the document.