Once again you have failed to provide any cite apart from "look at the files". There's no evidence that the police made any attempt to trace this individual is there?
It was a man standing at a wall...how do you expect them to investigate it further than they did?
On page 800, the interview with TASMIN MILBURN SILENCE is presented, who saw on two occasions and on several other days, an individual observing the apartment from which MADELEINE disappeared. A photo-fit was created based on the witness' indications . . . diligences were performed which led to the identification of MICHAEL ANTHONY GREEN, who was the target of diverse diligences without incriminatory results, pages 632 to 726 of Volume III, Appendix VI. Beyond this individual, there were other diligences performed at this level, also without useful results for the investigation, as is explained throughout Appendix VI.
Still on Appendix VI, pages 504 and in the following, it was investigated a situation relative to two individuals, NEIL BERRY and RAJINDER BALU (complementary inquests requested in the letter rogatory), specifically relative with the first one, whose information was crossed with the above aforementioned witness, TASMIN SILENCE, namely to what concerns the photo-fit, having this one made clear that it was not that same individual.
There you go.....the man Tasmin saw was identified so you can rest easy.