This story investigated the validity of a forensics technique, comparative lead bullet analysis, that has been used by the FBI crime laboratory since the late 1960's. FBI scientists determine the trace metal profile of a lead slug and then compare bullet profiles. They found there was not a solid scientific backing for this technique and that new research indicates that the conclusions the FBI examiners drew about relationships between were, at best, unwarranted. There was never evidence to conclude that the fact that two bullets share similar trace element profiles means they are in some way connected, and there is now evidence against that conclusion. This is important because the technique is commonly used in murder cases where traditional ballistics cannot be used and, often where there is little evidence.