Sarah Blumberg and Jennifer McMillen were working at an ice cream shop. A male entered the store. After placing an order, he brandished a gun and ordered one of the employees to put the store's money into a bag. He forced the employees into the store's walk-in freezer. The employees stayed there until they heard a customer enter the store. They called the police. No physical evidence was recovered. They helped the police prepare separate composite pictures of the robber. Nine days later, Blumberg observed a photographic line-up which included D's picture. She identified him as the robber. Five months later, McMillen saw the same photographic line-up. She identified D. P's case was the eyewitness identifications. D offered an alibi defense, maintaining that another person had committed the robbery. D wanted Michael G. Johnson, Ph.D., J.D., an expert in the field of eyewitness identification, to testify. P objected because it would not assist the jury in deciding the identification issue. The court refused to admit Johnson's testimony. The court allowed a proffer for the record and the expert's testimony would have covered topics: 1. the process of eyewitness identification; 2. the relationship between stress and memory of an event; 3. cross-racial identification; 4. the confidence the witnesses have in the accuracy of their identifications and the actual accuracy of their identifications; 5. the effect of time on the accuracy of memory; and 6. the suggestibility of the photographic line-up used in this case. D was convicted and appealed.