Did they get him for just a deposit? How did he pay?
Well looks like they are stupid enough to leave most of their facebook account open so get on to friends and hassle friends and family and tell them exactly what they are like.
If he sent the money through paypal as friends and family contact them and say it was fraudulent and if you don't get the money back then it will be in the hands of the police, also report them to the police and print out all the paperwork and show them everything. Just basically do as much as you can to cause them hassle etc.
If it was on ebay /marketplace then get screenshots of both their accounts and post up your own for sale ad with their pictures explaining what they are like.
Hopefully it wasn't a lot he was taken for, I got taken a couple of years ago by a guy down in wales/chelmsford area. Luckily I found out he was trying to scam me before I sent more money so I was only out by about 50 quid. Spoke with paypal and the scammer had used his sisters account, had a bit of an argument with her because paypal gave me the money back. Could have been a lot worse he had been on audisrs and got pictures from for sale ads and used them to try con me out of more money.