Topography measurements and applications in ballistics and tool mark identifications.

The application of surface topography measurement methods to the field of firearm and toolmark analysis is fairly new. The field has been boosted by the development of a number of competing optical methods, which has improved the speed and accuracy of surface topography acquisitions. We describe here some of these measurement methods as well as several analytical methods for assessing similarities and differences among pairs of surfaces. We also provide a few examples of research results to identify cartridge cases originating from the same firearm or tool marks produced by the same tool. Physical standards and issues of traceability are also discussed.

A density gradient technique for use in forensic soil analysis

A high-density aqueous salt solution for the preparation of density gradients is presented. It has been used successfully by the authors in forensic soil analysis. It has a density range that allows for the separation of a soil specimen's heavy mineral components. It has no odor or toxic fumes, which eliminates the need to use a hood during preparation, and is far superior to the organic liquids normally used to prepare density gradients. This liquid should cause many forensic scientists to reexamine their attitudes towards using density gradients in forensic soil casework.

Trajectory reconstructions. I: Trace evidence in flight.

This paper reviews the use of trace evidence recovered from spent bullets in helping to establish trajectories. The use of information derived from such trace evidence combined with that from geometrical techniques of trajectory reconstruction and other data is discussed. Five cases are reviewed in which the analysis of trace evidential materials adhering to bullets was used to help reconstruct the event.

The morphology and evidential significance of human hair roots.

A discussion of the morphology of human hair roots is presented. In addition to descriptions of variants of the root appearance for hairs removed from follicles in the three classical growth phases, several other commonly occurring root configurations are described and illustrated with photomicrographs. The possible evidential significance of each in certain case situations is discussed.

Trace evidence--the invisible witness.

This paper reviews the use of microscopic trace evidence in actual casework. Three cases are discussed in which the microscopic analysis of trace evidence was used to: associate the people, places, and things involved in the incident; reconstruct the event; and describe the occupation(s) of the participants. Each case is discussed in detail from the initial stages of the investigation through the use of the trace evidence during the investigation and at the trial.