I don't want to sound like a stuck record, but this is extraordinarily relevant to the Megrahi case. He was convicted entirely on the basis of alleged eyewitness identification.
Here is what he actually looked like in 1987 (the encounter with the eyewitness took place in 1988).
http://www.vetpath.co.uk/jref/m-1987.jpg
The encounter between the eyewitness and the suspect took place in
November 1988. The eyewitness wasn't identified as a potential witness until
September 1989. During the following year he was shown a large number of photos of people who may or may not have been the person he saw. He picked out several as "resembling" the man he saw. He also produced a photofit and an artist's impression of the man he saw, which actually look like two different people.
It wasn't until
February 1991 that he was shown a picture of Megrahi. That is well over two years from the actual encounter - an encounter between a shopkeeper and a customer, which may have laster for 30 minutes at the most.
This is the picture he was shown.
http://www.vetpath.co.uk/jref/m-czech.jpg
Initially, he didn't pick out this picture at all, saying all the pictures he had been shown were too young. The investigators told him to go back and pick someone anyway. The way this was conducted was an open invitation for a "Clever Hans" trick, with the policemen all being aware of which picture was the suspect's, and able to see which picture the witness was looking at at any given moment. Megrahi's picture was also of grainier quality than the others. At the second time of asking, he picked that photo, but only saying that it "resembled" the purchaser.
That did it. The investigators had what they wanted. They never did show the witness the decent likeness of the colour photo, to confirm the identification, "for fear of tainting what he has already given us". In other words, for fear that the witness might say, no, sorry, that wasn't him.
Years passed. Years during which other photos of the suspect appeared in newpapers and magazine articles - articles the witness collected. In 1998-9 there was an absolute flurry of such articles. One of these was taken from the witness only four days before he attended the identity parade - a magazine he'd had in his possession for four or five months, and which had a good, up-to-date picture of the suspect as he looked in 1999.
In April 1999 the witness attended an identity parade. By this time the suspect looked like this.
http://www.vetpath.co.uk/jref/m-1999.jpg
Remember, the only picture the witness had actually identified up to this point is the black-and-white one above.
Just to be sure, at the identity parade the suspect (who was 47) was one of the oldest men in the line-up, even though if the witness's original statement from September 1989 was accurate, the man they were looking for would by then have been in his early 60s. (Some of the men in the line-up would only have been in their teens at the time the witness saw the man he described then as being about 50 years old - Megrahi himself was 36 at that time.) And to make it even surer, all the "foils" were wearing trainers, while Megrahi was obliged to wear a pair of bright red shoes.
Even then, although the witness picked out the "right" man, he again said this was only someone who "resembled" the man he'd seen for a short time over ten years previously.
That was the basis on which Abdelbaset al-Megrahi became "the Lockerbie bomber". I kid you not.
Rolfe.