Here's one legal opinion I found online. It does not address nudity or an individual portrait, though. It seems to matter whether it is considered news:
http://www.lawguru.com/legal-questio...ed-107050420/a
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Publishing photos of people without their permission
I have prepared a color brochure to market casino parties in Florida. On the brochure I am planning on using still shots taken of people at a recent casino party. Gambling is not allowed in Florida. This is merely a recreational, no-money-involved endeavor. My question is: Must I get permission from all the people appearing in these photos in order to use the pictures on the brochure? Or is it within the law to show photos of people having fun around a mock gaming table without having them sign a release?
Thanks for your opinion!
=== ANSWER ===
Generally, people in public places have no legitimate protection if their photograph is taken as part of a larger photograph. News photos of a disaster, for example, do not require a release from every person appearing in them.
The use of an individual's likeness in a photograph being exploited for commercial purposes may well be a different story. In this event a release is probably required.
Due to the sensitive nature of the photographs you describe, you would be best advised to obtain releases from those identifiable in them to avoid future litigation if you use them commercially.