Crime Scene Investigator Network

Crime Scene Investigator Network Newsletter

MAY 2018
This month's newsletter is brought to you by the 2018 CSI Summer Academy

Optimized Development of Latent Fingerprints
on Unfired and Fired Brass Cartridge Casings

Katie Jo Sullivan

Cartridge casings found at crime scenes may contain fingerprint evidence to introduce or help convict a suspect; however, there are few articles on the subject of the best method to develop fingerprints on cartridge casings. The purpose of this research was to compare the best development methods for unfired casings found in previous research along with other commonly used development methods. After the most effected method was determined, that method was then applied to fired brass cartridge casings. Five different methods and five hundred unfired .40 caliber brass cartridge casings with one fingerprint on each were used. The two techniques that yielded the best results were cyanoacrylate fuming followed by gun blue followed by BY40 and cyanoacrylate fuming followed by BY40 followed by acidified hydrogen peroxide. The technique that produced the highest average of fingerprints of comparison value was cyanoacrylate fuming followed by gun blue followed by BY40; this method was the method chosen to be applied to the fired cartridge casings. Phase II consisted of firing fifty .40 caliber bullets from a .40 caliber handgun after one sebaceous fingerprint was placed on each casing. Although cyanoacrylate fuming followed by gun blue followed by BY40 yielded clear fingerprints with unfired casings, this method did not produce any clear fingerprints on fired cartridge casings due to the factors a casing sustains during the firing process.


Fingerprint comparison and examination has been used to connect suspects to evidence and crime scenes since 1892, when a trial in Argentina used a bloody fingerprint found at a crime scene to convict Francisca Rojas of murdering her two children (Lee and Gaensslen 2001). The science behind fingerprint examination involves the patterns of ridges and furrows found on the palms of the hands and the soles of the feet. These ridges have pores that secrete perspiration, and when a finger comes in contact with an object, the perspiration can leave an impression of the ridges. The use of fingerprint comparison to convict a suspect relies on the concept that ridges of a fingerprint remain the same over the course of one's lifetime, and that no two people have the same fingerprint (Lee and Gaensslen 2001).

The National Institute of Justice describes three different levels of detail used to describe the characteristics of a fingerprint. First level detail describes the overall direction of ridge flow in a print. A print described using first level detail would be classified as a loop, arch, or whorl. First level detail is a class characteristic and cannot be used for individualization. Second level detail describes the path of an individual ridge. Ridge endings and bifurcations, where one ridge splits into two, can be seen if second level detail is present. Second level detail can be used for individualization. Third level detail includes the morphology of a ridge. The texture and position of pores of the ridges can be seen if third level detail is present (NIJ 2011).

An example of evidence that could contain fingerprints is cartridge casings. Before a bullet and its casing are loaded into a gun, it is presumably handled and marked with fingerprints. After the bullet has been fired, its casing is ejected from the gun. If not retrieved, this casing is left at the scene. Fingerprints left on casings found at a crime scene could be evidence to introduce or help convict a suspect. However, there are few articles on the subject of the best method to develop fingerprints on brass cartridge casings.

Fingerprints are rarely recovered from fired cartridge casings due to the factors a casing sustains during the firing process. One factor affecting the likelihood of developing a fingerprint from a casing is the friction between the casing and the gun through the firing process. Friction occurs between the magazine and casing as the casing is loaded into the magazine. Friction also occurs when the casing enters the chamber before firing and when the casing is ejected from the chamber after firing. The casing is exposed to high temperatures and combustion gases during the firing process that can affect the oils and sweat from a fingerprint on a casing that would be used in development (Champod et al. 2005).

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This Month's Featured Resource on the Crime Scene Investigator Network Website

The beginning of this manual is a list of processes and procedures for different surface types. Also included are processing sequences that specifically involve prints that are left in blood. Following these lists are details for each process that is currently implemented in the Latent Print Unit (LPU) of the Federal Bureau of Investigation (FBI) Laboratory.

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Featured Video Presentation
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Developing Latent Fingerprints with Black Powder

Learn the basic technique for processing latent fingerprints by dusting with black powder.

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Rapid City Police Department, Rapid City, South Dakota, USA

Final Filing Date: May 29, 2018
Responds to major crime scenes; collects and analyzes evidence; preserves and documents crime scene and evidence through photography, measuring and scale drawings; prepares written reports. Operates analytical equipment and instruments using standard technical and scientific methods to perform specialized forensic examination of evidence and prepares written reports
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Denver Police Department, Denver, Colorado, USA

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DNA Analyst
Colorado Springs Police Department, Colorado Springs, Colorado, USA

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Perform serological testing and analyze body fluid stains and samples on a variety of evidence types related to various criminal cases. Perform forensic DNA analysis from DNA extraction, quantification, and PCR setup, through analysis using specialized analytical instrumentation to develop DNA profiles. Interpret analytical results of DNA testing through use of genetic typing software.
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Computer Forensic Analyst
Racine County Sheriff's Office, Racine, Wisconsin, USA

Final Filing Date: May 31, 2018
Preview and analyze sensitive materials involving Crimes Against Children. More specifically, support members of the ICAC Unit with viewing and documenting highly sensitive video and data involving juveniles to ensure successful case outcomes. Provide investigative support by organizing and analyzing computerized information in computerized crime investigations.
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Latent Print Examiner
Tacoma Police Department, Tacoma, Washington, USA

Final Filing Date: June 1, 2018
Develop, preserve, and transport recorded fingerprints, latent prints and evidence collected at crime scenes; prepare testimony and testify in courts of law; process evidence for latent prints using sophisticated chemical, physical, optical and computerized scientific analysis techniques; provide formal and informal training to law enforcement officers, staff and outside agencies in the collection and preservation of evidence.
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