Before the blockchain not been created. The bitcoin uses in anything bad. Like they use bitcoin to pay drugs and they use money laundry to make sure there money is safe and no one can trace the amount of the money. But the blockchain created the bitcoin now is transparent if any one will do money laundry it can be traceable.
Yes the drug pushers use bitcoin before. It used for the payment and also in money laundry. They use money laundry because it will not traced where the money come from and it didn't know that what is the purpose of this money.