US authorities have for years wanted Snowden returned to the United States.
Greenpeace Russia declared the situation an "ecological & environmental disaster".
A day before her death, police officers and investigators had searched her apartment.
Alexei Navalny is demanding "the publication of proof and facts".
A former traffic cop turned Messiah and his right-hand man - a former boyband drummer - have been arrested.
Navalny fell violently ill on a domestic flight in Russia last month.
Navalny, President Vladimir Putin's highest-profile critic was poisoned with Novichok last month.
One of the first doctors to treat him says the symptoms were there - but no poison was found.
It's declined opening an investigation into the incident.