Bitcoin mixer is the dead end for all the investigation in case this blockchain criminal database will be implement. There is no way to track a transaction that process by mixer. This article show us that Bitcoin is traceable and not anonymous at all.
Of course not, Bitcoin should also fit into legal framework and that means that we need to sacrifice a part of of our privacy and anonimity and there is no sense in fighting it.
The only thing I used Bitcoin because it was anonymous and decentralized. If ever this feature will be compromised then it's not really the use case of bitcoin. We should not compromise our privacy in exchange for finding this criminal. Exchange must tighten there security because the problem starts there or maybe they cooperate with them.
Of course Bitcoin per se is not complete anonymous.
For me this is already bonderline censorship, and I don't like the idea of our addresses being registered as well, worst idea. I guess criminals will again try to outsmart they investigators, they can used mixers which they have done so, or use other coins besides Bitcoin and the most logical choice will be Monero, which has started already.
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https://www.coindesk.com/argentine-telecom-hackers-demanded-7-5-million-in-crypto-as-ransom)