It doesn't really affect my point - a witness knows what they SAW and what they HEARD. They get that wrong (genuinely) ofetn enough. They are NOT used to give an opinion as to WHY something was being done or said, or (usually) WHO the person was, certainly when it is a peripheral part of the incident (people going towards the central bit, or away from it).
An investigator does not take the witnesses word for it - they note what is allegedly seen and heard and then see how that fits with everything else, giving things more or less weight dependant upon reliability.
The MEDIA, in allowing witnesses to report LIVE and wth reporters using leading questions and actually encouraging speculation do exactly the WRONG thing and, once a story is out there, it gets a life of it's own. It is a very real problem which has got significantly worse over the last ten or fifteen years.