You'll have a very, very hard time in pursuing legal action against bitcoin cheaters or scammers. These are shrewd people who always find ways to evade authorities. Usually these cheaters are based overseas with anonymous identification or using fake names and addresses. If you have been cheated and your bitcoins snatched away, say goodbye because there's simply no way to take it back.
A very crazy hard time really. Who is going to be held responsible since it is not like the scammers or bitcoin cheaters as the OP stated will end up leaving traces of who they really are in the first place. Unless one is ready to take a lot of resources into pulling such a thing off which would not eventually be worth it anyway, it is just best to move on and accept that what is done is done and also learn not to fall for such pranks again.