Criminals use everything with value to finance their illegal activities. Bitcoin is only one of the many value tools that they can use.
So, yes. Bitcoin is being used for criminal activities.
Agree to you I think criminals are using various means to deceive law enforcement. although with bitcoin is very safe but I'm sure they do not just use bitcoin for their illegal activities
especially of course there are those who do not know what is bitcoin. so they also had to use a fiat for illegal activities
Various forms of transactions were made by criminals. At present with the ease of transaction bitcoin is getting popularized among them. So as a part bitcoin is also used in illegal transactions.