Can I take action against employee that sent nude photos at work

Yep!
There may or may not be any criminal aspect to what they did (it could depend on the content (context) of the photos), but there is probably a sexual harassment issue there (I cannot see why not at this point from what little information you provided) - it seems fairly straight forward.

I would say there could be many civil remedies you as the wronged person may have, but a lawyer would need all of the facts. If the individual posting the pictures did not own the copyrights to those images, you could pursue a copyright infringement claim and privacy claim.

Far too many variables exist. In general, many lawsuits are filed against people who posted nude pictures without permission.

Good luck to you. You should consult with a local attorney to determine your rights and the best remedy for your situation.

You might find my Legal Guide helpful "How to Choose A Lawyer For You"

http://www.avvo.com/legal-guides/ugc/how-to-choose-a-lawyer-for-you

You might find my Legal Guide helpful " What Do I Tell My Lawyer"

http://www.avvo.com/legal-guides/ugc/what-do-i-tell-my-lawyer

God bless you. I am licensed in Chicago

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