I don't expect any parent to suspect their child commit actual crime, especially if their child have no history of doing criminal activity or really bad behavior. Regardless, monitor or asking them some details would be great regardless considering risk they may fall into scam or invest on something without actually knowing the risk.

To OP, i don't know where you and that father lives. But depending on where you live, not reporting someone you know committing crime may cause legal trouble. Have you and him consider taking next action?