A question for prosecutors . . . seriously

I don't know if any prosecutors read this blog, but I would really like to hear their input on this issue if they do. Let's say you have a purse-snatching case involving two perpetrators. The victim in the case gave the police descriptions of both suspects. The next day, the victim sees someone in town who she believes was one of the men who stole her purse the day before. She calls the police, and they identify the individual. Later, the police prepare two photo line-ups for the victim. One includes a picture of the man she saw a day later and called police about. The other includes the picture of a suspect police developed based on her original description. The victim positively identifies both suspects. No other evidence ties either individual to the offense. Now, let's say that you receive irrefutable proof that the suspect developed by police could not have committed the offense because he was in jail at the time. The victim is informed of this, but is still confident in her identification of the man she saw the next day. If you are the prosecutor on this case, what do you do?