I am posting to Legal because more and more of these cases are going to court and leading to convictions. If you think it belongs on Erotic Highway (where most SD stuff is discussed) or General (if it's sufficiently general), you can ask TER to move and that's fine with me.
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I can't post specific links because most of the news stories contain personal names. However, if you search "seeking arrangements tinder extortion" (maybe throw in 2017) or something like that you should get some hits.  
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A 2017 case in Olympia, WA that ended up with the SB being convicted and incarcerated for (brutally) extorting at least three SDs for over $300,000.  Maybe as many as seven.
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A Charlotte, NC SB extorted $250k. (paywall for remainder of story)
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No names in this article:
http://nypost.com/2016/05/18/sextortion-is-the-newest-way-tinder-can-ruin-your-life/
Sextortion is the newest way Tinder can ruin your life  
(Warnings and suggestions regarding obvious (to TER readers, I hope) mistakes about social media.
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Sorry I can't be more specific. Be careful out there!