Basically anyone IDed as a perp by a victim in a rape case is doomed. Doesn't necessarily mean prosecutorial malfeasance, but in many cases it is - they'll subtly encourage a witness to pick SOMEBODY out of a lineup or mugbook, and then after that egg them on to become certain of their identification because they want to close the case.
Enough of the general public is completely ignorant of the fact that eyewitness testimony, given in good faith, can be horrendously wrong, that there are lots of guys like this poor guy.
A lot of prosecutors have so called "victims advocates" or some other group of employees. Their job is to sit on witnesses and make sure that they tell the "right" story and don't change their testimony before or during trial.