The scientific method, which has evolved from the work of many persons over the course of 2,500 years, is a way of observing; then thinking about; and finally solving problems in an objective, systematic fashion. There are five main steps involved in the scientific method: stating the problem, forming the hypothesis, collecting the data by observing and experimenting, interpreting these data, and drawing conclusions. Terms used in a discussion of the scientific method are defined. Although this description of the method emphasizes induction as a starting point, deductive logic is nevertheless an integral part of it. Criminal investigation generally commences as an inductive process. Actual cases are used to illustrate application of the scientific method to criminal investigation. Finally, a table compares evidence and proof in science, law, and criminal investigation. Six references are supplied.