John,
Let me summarize the FW testimony. The police told RW not to speak with LF, one of the few instances where they did the right thing regarding potential eyewitnesses. Against police instruction Ms. W contaminated Ms. W’s memory then probably lied about it. Her credibility has to be judged in light of her actions, and her act contaminated Ms. F's memory. Moreover, Ms. F was shown to be mistaken about the circumstances of seeing LM's photograph, further lowering the probative value of her testimony. On top of that, this was a dock identification, and every source I have consulted states in no uncertain terms that dock identifications are highly unreliable. Then there is the lack of agreement between their description of LM vs. the description of people who actually knew him and saw him in Newbattle. Furthermore, this was a sighting of a stranger from a car, hardly an ideal set of circumstances.
Now let us consider the interpretations of their testimony. If FW were absolutely correct, it would have little probative value anyway, putting LM a few hundred yards away from where he said that he was. If they saw him elsewhere (meaning if the recollection of the jogger were correct), it would put Luke further from the path, shortening an already dubiously short timeline. The alleged sighting would be more exculpatory than inculpatory.
Over the course of several months I provided quotes and citations in the “Laughable eyewitness testimony” thread documenting correct versus incorrect procedures for potential eyewitnesses. These quotations cover more than just the FW testimony. Moreover, the Andrew Malkinson case illustrates the danger of convictions based on faulty eyewitness testimony and puts an exclamation point to the ideas encapsulated in written guidelines. It is not surprising that false eyewitness testimony is the leading cause of wrongful convictions. Discussions which sidestep the arguments made and the examples of people wrongfully convicted given are unserious, among other adjectives.