Monthly Archives: April 2013

Magnetic Powder

By Pat A. Wertheim

This article originally appeared in Minutiae, the Lightning Powder Co. Newsletter, #43, July-August 1997.

Even though magnetic powder has been available since the early 1960’s, many latent print examiners and crime scene technicians are still not using it to full advantage. Magnetic powder adds a wide range of flexibility to one’s resources. In general, magnetic powder is used on non-magnetic surfaces, and regular powder on iron-based surfaces. However, regular fingerprint powder is inappropriate for some surfaces, including many plastics and textured surfaces, where magnetic powder develops latent prints very well. Textured surfaces such as vinyl imitation-leather or lightly textured automobile dashboards or door panels often respond well to magnetic powder, where regular powder would pack into the low places in the texturing and make development of a good latent impossible. In addition, using the “hot breath” technique, also known as “huffing” works better with magnetic powder than with regular powder. Continue reading

Trace Evidence: Hair

by Kathy Steck- Flynn

Edmond Locard was the founder of the Institute of Criminalistics at the University of Lyon in France. Locard believed that that when on person came in contact with another person or object a cross transfer of minute particles occurred. This theory became known as the “Locard Exchange Principle”. Locard believed that crimes could be solved by inspecting the “dust particles” carried to and from a scene. This science is known today as criminalistics and has led to the rise of the forensics laboratory (from Mount Royal College background notes FORE 4407 section 3: Unit 4) Francois Goron, head of the French Surete, seems to be one of the first modern investigators who tried to use hair to identify a killer. In his first case hairs found clutched in a dead woman’s hand could not be identified as human simply because there was no information on the subject.

The inability of the scientific community to distinguish between animal and human hair raised interest in the analysis of hair. In the years that followed researchers began to collect information about the structure of human and animal hair (Block, 1979). In 1899, several years after his original failure, in a case known as “L’affaire Gouffe” Francois Goron was able to establish that a murder victim’s hair had been dyed. Establishing this simple fact led to the identification of Gouffe’s body and subsequently to the arrest of his killers (Block 1979). Francios Goron had successfully used forensic hair examination to solve a crime. Continue reading

Interpretation, Collection and Preservation of Glass Fragments

By Kathy Steck-Flynn

A man is found dead in an abandoned house. Upon examination the medical examiner finds that the man was killed by a single gunshot to the head. Three local teens where observed near the house two days earlier. They are picked up and questioned by police. When pressured, the teens admit to having stolen one of the boys’ father’s guns. They had taken turns shooting at the windows of an abandoned house.

The teens admit that John shot the gun first, then Jay and last was Fred. At the scene the investigators find three bullet holes in a window. They analyze the angle of each bullet hole in relation to the victim and find that the bullet which passed through the far right side of the window pane is the one which fatally wounded the man. Continue reading