OpenCV application - face comparison

We have a corpus of around 10,000 faces (mugshots). We want an application that takes a different picture and reports the 5 faces from the corpus that look more than the different one (note that there won't be a perfect match). The application will display the 5 best match and allow the user to pick the best one so the system uses user feedback for learning. Other than OpenCV there's no requirement - the interface will be a simple web site that you can develop in any environment you feel comfortable on.