There is a way to do a photo lineup constitutionally IMO with only lacrosse players but it's not worth digressing to go into it
The photos can't be unduly suggestive, and the cop running the line-up must not know if the suspect is in the array. If they're all lax players in the photo array, and it was known that everyone at the party were Duke lax players, then the cop knew the suspect was in the array - had to be. Each array is supposed to present sequential photos of similar looking guys.
Perhaps of interest to you: http://72.14.203.104/search?q=cache:VUJJ9zOf6rwJ:www.law.duke.edu/innocencecenter/causes_and_remedies.html+north+carolina+law+photo+line-ups&hl=en&gl=us&ct=clnk&cd=7