Criminals can use anything in the world, this may be USD, EUR, RUB, CNY, JPY, anything in other word. There is no need to mention BTC for criminal activity and other bad purposes here.
I also think it is not bitcoin's fault if criminals are using it. Bitcoin has many advantages which is beneficial to its users and criminals make use of this. They take this as an opportunity to make their plans work. Criminals will always be criminals no matter the platform they are using.