The death of Alexei Navalny - an imprisoned and outspoken critic of Russia's president Vladimir Putin - is prompting human rights experts to ask who's next.
The penal colony where Mr. Navalny died sits above the Arctic Circle, and is largely cut off from the world.
Russia's presidential elections are due to take place in one month.
Mariana Katzarova is the first ever UN Human Rights Council-appointed independent expert on Russia.
She spoke to Ingrid Hipkiss.
