Developing a portable cyanoacrylate fuming chamber for fingermark detection and enhancement at crime scenes

Abstract

Fingermarks are commonly found at crime scene and are routinely used as a form of comparative evidence for identification. Latent fingermarks are the most ubiquitous type of fingermarks found at crime scenes and are also prone to incidental destruction through the recovery, packaging, or transportation processes. Latent fingermarks often require either chemical, optical or physical development to be visualised and later used for comparison purposes (Champod et al. 2016; Hawthorne, Plotkin & Douglas 2021). Cyanoacrylate (CA) fuming is a chemical method of developing latent fingermarks on non-porous surfaces and is routinely used at forensic laboratories as one of the initial steps in the recovery process (Champod et al. 2016). CA fuming is a sensitive technique which involves heating CA monomers within a sealed, high relative humidity (RH%) chamber, which then polymerise along the friction ridge residues forming a hard, white polymer (Holder, Robinson & Laub 2011). CA fuming is traditionally a laboratory-based technique, as this allows for much greater controls over both internal and external conditions, however, portable CA fuming does exist Champod et al. 2016; Jones et al. 2019; Holder, Robinson & Laub 2011; Geller, Springer & Almog 1998; Moses Daluz 2018; Ramotwoski 2012). Portable CA systems offer unique benefits for crime scene investigators but also present some difficulties with implementing the use of these systems routinely in casework scenarios, such as expensive componentry, 240V power requirements and difficulty controlling internal conditions which can reliability and repeatability. This project set out to develop an improvised portable CA fuming chamber, following on the work completed by Vrzic (2022), with the aim for it to be reliable, affordable, and completely portable. This project initially focused on optimising the componentry to operate via 12V, as opposed to the prior chamber which still required 240 V power. Once the componentry was optimised to operate via a portable 12V power source, a comparison of the portable chamber in pseudo-operational conditions to a standard laboratory chamber was conducted to assess the development capabilities. This used various donors, various substrates, and testing under a range of ambient RH% conditions, to represent conditions which may be encountered during casework. During this testing, it was found that at moderate RH% (40%-60%), the portable CA chamber was able to successfully develop fingermarks similar to a laboratory-based CA chamber, for a range of donor strengths on metal, glass and plastic substrates. This was particular observed at moderate (40% - 60%) and high ambient RH% (60% - 70%). It was also noted that the largest factor that influenced development was the ambient RH%. At low ambient RH%, it was difficult to increase and maintain the internal RH% of the portable chamber, which is believed to have caused negative effects on development. Ambient conditions of 40% or lower, causing reduction in quality of the developed fingermarks on development in the portable CA chamber.

Date of Award	2024
Original language	English
Awarding Institution	Western Sydney University
Supervisor	Brenden Riley (Supervisor), Robert Ebeyan (Supervisor) & Val Spikmans (Supervisor)