Interesting research coming out of Uni of Cambridge. Can bitcoins be tracked? ... used to have issues with tainting the bitcoins but current technology has lead to practical ways to trace stolen bitcoins. im not sure what this means for you and me, like what happens if somehow stolen bitcoins land in my hands... but interesting nonetheless.
Video: Stolen Bitcoin Tracing - Computerphile; practical way to trace stolen bitcoins it is not a new thing. that is the unique of blockchain itself. Blackchain is decentralized and transparent system. everyone can trace bitcoin flows through wallet to wallet addresses. another unique of blockchain is anonymity. even you can trace where bitcoin flows, you can not know who stole it.