When physical evidence arrives in the laboratory. it is in a sealed plastic bag and Physical evidence refers to guns, knives, shirts with blood droplets and even documents found at a crime scene. But the greatest technological advancementin forensic science over the past decade have occurred in the area of trace evidenc Trace evidence refers to very minute evidence like strands of hair, skin cell blood specimens, or fingerprints. Equipment used to analyze this evidence includes high-powered electron microscopes, digital image processors, toxicology analyzers for drug testing, paint analyzers, and even the ability to cast sh textures and imprints.