Dr. Bastawros' specialized knowledge pertains to the characteristics of metals and the physics of how they behave under the stress that is sufficient to fracture a particular metal tool. The relevance of this science to criminal investigations occurs in cases where a metal tool such as a knife or chisel fractures in the course of a crime, leaving one piece at the crime scene and the other piece retained in the offender's possession. A match would place the offender at the crime scene. Issues discussed in the interview include the types of fractured metal likely to be found at a crime scene (hard, brittle metals vulnerable to fracture). Dr. Bastawros describes the procedure used to match one piece of metal from a fracture with another piece and derive a statistical probability of a correct match. The interview focuses on distinctive characteristics of metals and of a given fracture of a metal. Requirements for visualizing the distinctive features of metal and their fracture patterns are discussed, along with the development of mathematical algorithms necessary to indicate the likelihood of a match between separate parts of a metal fracture.