The subjects, who represented 6 percent of the 4,171 sworn officers in Kansas, were pre- and posttested (during the first week of December 1987) using a 36-item instrument with 4 multiple-choice answsers per item. Participants were divided into 4 treatment groups of 43 in lecture, 60 in control, 65 in case study, and 69 in videotape. Each group participated in a 2-day, 14-hour Use of Deadly Force seminar at Kansas State University. One-way analysis of variance with Tukey's post hoc was used to analyze the data. The case study group decayed only minimally on the learning retention measure over the 1-year period. Learning retention for the lecture group decreased significantly to nearly the pretest level. Although not significantly, the videotape group also decreased. It was concluded that police trainers can use case study, and to a lesser extent, videotape, as training techniques without fear of inhibiting learning. 40 references and tabular data. (Author abstract modified)