Sorry for my english and my delay
I had to sell an Antminer s9 on olx (like ebay) and they called me to ask me if it is for sell and after that he asked me if i want to sell bitcoin becouse his bank account is bloked.
yes, I made a small transaction before the main transaction to make sure it appears in their wallet. They used jaxx live wallet on an Iphone. I could enter the application on their phone but I could not withdraw to perform operations. They said he would go outside to talk on the phone and leave the phone on the table and rest assured that the money was there. I realized and caught one and called the police.