Having unexplained assets is not a crime and won't be at least in the US because of the constitution, worst case they could be subject to civil forfeiture. Assuming you did everything else right (full disk encryption, Tor on public wifi/LTE router that you alternate routinely, not using Google, etc) the anonymity of Monero means the government would have a very difficult time tying whatever you bought with the Monero to your actual criminal activity. Of course if you are involved in meatspace crime like drugs then maybe if you use these services they put you under surveillance and eventually find you with drugs in the trunk of your car.
Parallel construction: if you do enough crime-adjacent things, the likelihood that you are also engaged in crime makes you interesting to law enforcement.
Breonna Taylor (2020) - Louisville, Kentucky: Police officers entered the wrong apartment using a no-knock warrant, which led to the fatal shooting of Breonna Taylor, an emergency medical technician.
Eurie Stamps Sr. (2011) - Framingham, Massachusetts: Police raided the wrong apartment, and during the operation, an officer's gun "accidentally discharged," killing Eurie Stamps Sr., a 68-year-old grandfather.
As many have mentioned above, civil forfeiture cases for carrying cash are rare, but devastating to people who are originally from countries/cultures that don't trust banks or police.
Heh, it's a literal meaning of crime adjacent (presuming that the person in the actual target apartment was actually guilty).
I suspect anyone that was an early adopter of crypto is somewhat considered crime adjacent because so much of the early usage was silk road.
For a while after MtGox was hacked I used BTC-e (yes, I lost money in MtGox). It was later discovered(alleged?) that the operators of BTC-e were involved in laundering money for the MtGox hack[0]. I guess my very presence in that case would be considered crime adjacent.
I think pocketing any unlockable crypto-wallets you found along the way would cross the line. You could stick them into civil forfeiture and use the resulting cash to upgrade your department-owned car though.
