Time delays may mean memory for faces is more of a whole impression than an analysis of individual features. The issuing of a computerised image could be a flawed approach. But another problem is not just the time delay in the Madeleine McCann case but the very way the media has reported the crime could have damaged the possibility of correct identification.
Our memory is capable of incredible things; however, it does not work like a tape recorder, neither when memorising an event, nor when attempting to recall it. In court, eyewitness evidence is regarded to be among the most incriminating type of evidence.