That’s a good question. Is there anyone here who can answer that?

Edit: FTA:

Ukraine had requested Petrovsky’s extradition, but a Finnish court ruled on Dec. 8, 2023, that he could not be sent to Ukraine, citing concerns over prison conditions under the European Convention on Human Rights.

I Guess that we’re supposed to infer that this guy had been living in Finland for some time, and therefore was subject to their jurisdiction.