Who Held the Gun? Decipherment of Suicide-Homicide Cases Using the PDT Reagent

• NCJ Number: 191258
• Journal: Journal of Forensic Identification Volume: 51 Issue: 4 Dated: July/August 2001 Pages: 346-360
• Author(s): Amihud Leifer; Hagay Wax; Joseph Almog
• Date Published: 2001
• Length: 15 pages
• Publication Format: Article
• Publication Type: Report (Study/Research)
• Language: English
• Country: United States of America

Annotation

This article profiles four death investigations in which PDT (pyridyl-dephenyltriazine) field tests were used to help determine who held the lethal weapon.

Abstract

The PDT test, which has been successfully used to determine whether a person has handled a gun, is based on a chemical reaction between iron ions and the reagent PDT. The result can be seen by the appearance of a violet-magenta stain, which in many cases has the shape of the metallic parts of the weapon. The types of incidents in which this test can be helpful are numerous and varied. The most common type of case is suspected suicide. In such instances, the test can support the hypothesis that the deceased did, indeed, hold the weapon at issue before his/her death. At times the PDT test can show that the deceased held the weapon with a reverse grip. In other shooting incidents in which a potential suspect disassociates himself from the scene of the crime and contends, for example, that he did not hold the weapon, PDT can disprove his statement. In cases of murder-suicide, in which it is uncertain who is the victim and who committed suicide, a PDT test can help determine which of the two did not handle the weapon. When a suspect admits to having held a weapon but not the one in question, PDT reactions on the hand can sometimes either support or negate the suspect's contentions. This report provides four examples in the casework of the Israel Police in which PDT had an important role in determining the course of events. The cases described involved a suicide, a murder, a double murder and suicide, and a murder and suicide. Because of the effectiveness of PDT testing, the Israel Police Serious Crime Mobile Laboratory carries PDT field tests as standard equipment. Although evidence technicians apply the PDT field kit, only authorized experts are allowed to interpret the results. 6 figures and 12 references