I have never seen examples of criminals often using bitcoin for criminal purposes. I think they were just fakes. Now, when the popularity of cryptocurrencies has sharply decreased, these fakes do not make sense and they are no longer supported and distributed.
Don't know where have you been and i don't know why you do reach up Sr. member and you didn't able to see those examples since you had mentioned you never seen of examples.
If you do able to see on all negative or illegal usage of bitcoin in the market then you wont say this thing. I wont mention 1 by 1 but you can actually make a research.
Monero would be the best choice when it comes to total anonymity.