Maxim Borodin, 32, was found badly injured on the pavement under his balcony and taken to a hospital, where he died Sunday, according to his employer, the news website Novy Den (New Day).
Vyacheslav Bashkov said Mr Borodin had contacted him at 5am on April 11, saying there was "someone with a weapon on his balcony and people in camouflage and masks on the staircase landing". "But he didn't write anything and on the 13th the media reported that Maksim had been found under his balcony and he was in the emergency room".
In another report, local authorities said they were not treating the death as suspicious. Polina Rumyantseva, editor in chief of Novy Den, said that there was no reason to suspect suicide.
Mr Borodin, who had been looking to hire a lawyer, later called him back to say he was wrong and that the security were a part of an exercise. But suicide, she said, was an unlikely cause.
Last year, he gave an interview to a Russian independent channel TV Rain and talked about the controversial film "Matilda", and was subsequently hit on the head by an unknown assailant with a metal pipe, according to a Facebook post.
Mr Borodin was described as a "principled, honest journalist". It is claimed they were from the Wagner Group, a private army Moscow is said to be using in Syria.
Syria shoots down missiles over air bases
The reported strike comes days after the US, UK and France bombed Syrian military facilities over a suspected gas attack in Douma. A local reporter for The Arab News said Israeli warplanes were spotted in Syrian airspace just before the missiles were reported.
The group is reportedly bankrolled by Yevgeny Prigozhin, known as "Putin's chef" with links to the Kremlin. In February, he broke a story about Russian mercenaries who died in an armed confrontation with US forces near Deir-Ezzor, Syria. He was one of 13 Russians indicted in February as a result of Special Counsel Robert Mueller's investigation on charges he funded the "troll factory" in St Petersburg that allegedly tried to sway the U.S. presidential election in 2016. As the New Yorker noted, it was the first time in half a century that Russian and USA military forces had engaged in direct combat.
But Harlem Desir, the representative for freedom of the media at the Organisation for Security and Co-operation in Europe said Borodin's death was "of serious concern".
According to the European Federation of Journalists, more members of the media have been murdered in Russia than anywhere else in Europe in recent decades.
"I call on the authorities for a swift and thorough investigation", he said.
"This story is not about how the regime kills one journalist who writes on inconvenient topics", Volkov wrote on Facebook.