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The Nature of Forensic Science

Forensic science is comparative science. The properties of a sample from an unknown source or of an unknown material are characterized in as much detail as is practical. Those characteristics are then compared to characteristics of a sample from a known source or of a known material. To the degree that characteristics match (or don't match), certain conclusions can be made regarding the source or makeup of the material.

All fields of forensic science use this type of comparative characterization. It is used in firearms examination when a bullet of unknown origin is compared to bullets fired through the barrel of known guns. It is used in handwriting comparisons when an examiner seeks points of similarity between writing of unknown origin and standards from a suspect. It is even used in drug analysis when the properties of an unknown material are compared to those of a known standard.

The weight of the conclusion which can be drawn depends on the certainty of the characterization and the unusualness of the characteristics determined. A fingerprint comparison with 8 to 10 points of similarity would carry much more weight than a paint match with just color as the matching characteristic. However, a chartreuse paint color match would carry more weight than a medium blue one, due to the relative rarity of the color.

Analysis is performed using a variety of instruments, reagents, and solvents.

Analysis of physical evidence is conducted by eight specialized units.

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