The Paris-based organization Reporters Without Borders (RSF) is urging Russian officials to find the attackers who severely injured the late journalist Mikhail Beketov in 2007.
Beketov, 55, died in a hospital on April 8.
His lawyer said he choked to death on his food.
Beketov suffered brain damage and lost a leg and several fingers after a beating in 2008.
His attackers have never been identified.
Before the assault, Beketov reported he had discovered large-scale corruption surrounding the construction of the Moscow-St. Petersburg highway through the Khimki Forest.
In 2010, a Khimki court convicted Beketov of slander in a case brought by the town's mayor in 2007.
On April 8, RSF called Beketov "a symbol" of Russia's struggling civil society and said "it is more important than ever that his attackers be brought to justice."