Trace Evidence Recognition, Collection, and Preservation

Abstract

This chapter provides a foundation of knowledge that will enable successful processing of trace evidence in the forensic field. The trace evidence principles that are discussed include theories of transfer and persistence; proper trace evidence handling practices; recognition, collection, and preservation of trace evidence at the crime scene; and recognition, collection, and preservation of trace evidence in the laboratory. A primary transfer occurs when trace evidence from a particular source is deposited directly onto another surface. A secondary transfer occurs when previously transferred trace evidence is transferred to yet another surface. The chapter explains the uses of personal protective equipment in the field of forensic science. For the trace evidence analyst, the stereomicroscope is an invaluable tool. The magnification allows for targeted searches for fibers, paint chips, gunpowder particles, and any other debris of interest. The chapter also provides a checklist for evidence examination in the laboratory.