Having a competent person in court who can testify to precise details at the time of a crime can easily sway a case one way or the other. Many people have been lead to believe that an eyewitness merely identifies a face in a line-up or some other minor detail of a crime. In reality, a good eyewitness can help eliminate suspicion as much as create it. Here are some things to keep in mind if you should witness a crime yourself. This may appear to be the most obvious element of eyewitnessing, but it can get very complicated.
Facial features are the standard expectations- hair color, eye color, complexion, body hair, etc.
Such information is helpful, but what can be even more helpful is the physical information that can eliminate suspects. There may be quite a few dark-haired bearded Caucasians in the area, but very few with a Spiderman tattoo. Eyewitness testimony is notoriously 'flexible' when notes from different witnesses are compared, but if the same physical characteristics are noticed, it may help narrow down the list of suspects considerably. Mannerisms and accents. Listen for any abnormalities in their voices- stuttering, speech impediments, slurring of words.