The German police have successfully deanonymized at least four Tor users. It appears they watch known Tor relays and known suspects, and use timing analysis to figure out who is using what relay.
Tor has written about this.
Hacker News thread.

    • far_university190@feddit.org
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      20 days ago

      large club of people interested in technology

      edit: https://www.ccc.de/en/

      The Chaos Computer Club e. V. (CCC) is Europe’s largest association of hackers. For more than thirty years we are providing information about technical and societal issues, such as surveillance, privacy, freedom of information, hacktivism, data security and many other interesting things around technology and hacking issues. As the most influential hacker collective in Europe we organize campaignsevents, lobbying and publications as well as anonymizing services and communication infrastructure. There are many hackerspaces in and around Germany which belong to or share a common bond to the CCC as stated in our hacker ethics.