Of course. Though it depends, if you bought the bitcoin peer-to-peer with cash then it would be extremely difficult for people to know if your money was acquired in an illegal manner, they might not even care if ever they know. If you used services like Coinbase though, and the government finds out about illegal activity, then they're going to seize your funds.
This.
Who will be the deal manager and know that the trade is illegal.
If OP keeps asking these questions openly, then it's not that difficult for authorities to find out what's going on, or to at least start an investigation.
Common sense would be enough to find out the answer, but not everyone knows how to properly utilize common sense it seems.