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.
Well we know that bitcoins leaves a trail that anyone can follow but hackers and thieves are very smart and they can always try some strategies to try to confuse investigators somehow, to be honest I do not remember that any hacker that released a ransomware was arrested because of it, it will be interesting to know if someone knows if a hacker has been brought to justice