You are probably safe from possible arrest. The worst that could happen to you is that your personal information will be taken by the authorities. The way I look at it, there is no reason why you should be punished along with the real criminals. I don't even think the money used by the criminals to buy BTC will get confiscated. They should focus on trying to confiscate the BTC instead.

You are just selling BTC to anyone interested. You are not an investigator on the people you sold BTC to. Just like a money exchanger accepting clients without necessarily investigating whether they are going to use it for crimes or not. How would you know?