This may sound very stupid. I ended up trusting a client and taking on work without any upfront fee. In fact we worked out a 15 day payment cycle. Although I was a bit apprehensive I took a bold step and am now kicking myself because he just disappeared off the screen. I have found some of the work already posted on websites. Are there any Indian writers out there that can help me (this is because both me and the client are India based). I would truly welcome any inputs from anyone else too. No phone contact. I only have email ids. He posted a classified on Craigslist and that was it.
I would suggest that you are going to take a loss on your labor. The fact that he's already posting your content on websites means that he is experienced at this, and has more than likely done this before. He probably knows how to cover his tracks. You don't seem to have much to go on as far as finding this guy. Just remember, a mistake is not as big of a mistake if you learn from it. Sorry about all your work being for nothing like that.
Sorry for what has happened. It might not be possible to recover the money that you are owed, but if there is nothing that you can do to get back the funds, then perhaps all you can do is be patient and if it comes through, it comes through -> just trying to say dont burn your bridges or say anything just in case they need more time before they pay you... I have had people vanish for weeks, but finally came through and they had legitimate reasons. May I recommend that you look into other options. Like there are many sites like fiverr, where the users pay to the system, and once you deliver the work, the system pays you. Dwelling on your mistakes will cost you more rather then if you move on and focus on working on platforms that can protect you.
Where's the content hosted? If they're U.S. servers, you could send DMCA takedown notices. Even if they're outside of the U.S., the hosts might comply. You could screw him over this way--if a client paid him for the content via PayPal with a credit card, they can do a chargeback. Revenge is always nice, even if you don't get the money.
Why not post the same content using fiverr service in many blog post or Wikis. So in long run it will create duplicate issuse for him and ultimately has to take down the content.
Use content for yourself, learn from it.. contact him again in like one month if you have a stomach for it.