Robbie Coltrane's Critical Evidence plot
When a murder is committed, but there is no suspect, there are no clues, and maybe there isn't even a body, then the police face the toughest job. Evidence must be collected and analysed, but it's worth nothing if it can't be linked to a suspect. Most murder victims were known to the perpetrator and so it is often a relatively simple matter. Yet in about 20 percent of murders in the UK it is not clear what the exact circumstances were. Robbie Coltrane takes a closer look at a number of eventually resolved cases. In addition, those involved, including relatives, witnesses, specialists and police officers, are given an extensive interview.