Because of the semi-anonymous nature of Bitcoin, its used in ransomware attacks. Hackers breach networks and hold them hostage until payment is made to them. Hospitals and schools have been victims of these types of attacks. However, unlike cash, which was favored by thieves in the past, Bitcoin always leaves a trail in the blockchain that investigators can follow.
This topic is concern about cybercrime not bitcoin. Criminals can't avoid law enforcement just because they use bitcoin. Law enforcement always find the way to do their job. We should not blame bitcoin because of that, if Bitcoin is not exist then those hackers will find other methode to do cybercrime.