Third Chemistry Section

Physical substances derived from the suspect, such as single fibers, glass fragments, paint fragments, plastic materials, metals, and soils, are unconsciously left at the crime scenes. Also, those derived from the crime scene or the victim are cross-transferred to the suspect as a result of the contact between them during the conflict. This section is responsible for research on the analysis of physical evidence and related caseworks to verify the relationship between the suspect and the crime scene. Recently, trace physical evidence is recognized as being important to the criminal investigation, and a systematic system has been developed for the identification of trace physical evidence by morphological elemental analysis using sophisticated analytical instruments. Analytical methods to identify radioisotopes have been also studied.

Research on identification method for trace physical evidence

Automated melting point and refractive index measurement apparatus
This apparatus plays a significant role in the discrimination of minute glass fragments.

In the examination of trace materials, analytical methods are restricted by the very minute amount of available samples. To retrieve maximum information from the trace physical evidence for accurate identification, research on systematic analytical methods have been carried out using several sophisticated analytical instruments.

Research on discrimination method by comparison of trace impurity elements

Laser ablation inductively coupled plasma mass spectrometer
This instrument enables rapid and high-sensitivity elemental analyses of trace solid samples without complicated pretreatment.

Glass, metal fragments, and geological samples contain characteristic trace impurities derived from source materials and the manufacturing process. Research on the discrimination method for physical materials by utilizing these impurities as indices has been conducted using high-sensitivity analytical instruments.