Maxim Borodin fell from his fifth-floor apartment.
CNN  — 

A Russian reporter known for his investigations into Russian mercenaries in Syria died after a fall from his apartment in the city of Yekaterinburg, raising fresh concern about threats to independent journalists.

Maxim Borodin fell from his fifth-floor apartment and died Sunday, according to a statement released by his employer, Novy Den (New Day). Local police said they did not see any foul play, but his death prompted intense speculation among friends and colleagues.

Valery Gorelykh, spokesman for the Interior Ministry for the Sverdlovsk region, told CNN that Borodin’s apartment was locked from the inside, a fact that he said indicated “no one exited the apartment and most likely there were no strangers in there.”

Russia’s Investigative Committee, the country’s main investigative body, said there were no indications of a crime, and that multiple causes of death were being probed. Polina Rumyantseva, editor in chief of Novy Den, said that there was no reason to suspect suicide.

“We were able to visit the apartment of Maxim, together with the police and forensic experts on Friday, the intermediate conclusion is that Maxim fell out of the balcony of his apartment where he probably was smoking,” she said. “As Maxim had big plans for his personal life and career, there is nothing to support a verdict of suicide.”

Others fear his death may not have been accidental.

Borodin’s friend, Vyacheslav Bashkov, wrote on Facebook that Borodin contacted him early in the morning on April 11 and said his building was surrounded by armed “siloviki,” or Russian security services, wearing camouflage and face masks.

According to Bashkov, Borodin believed his apartment was about to be searched and that the security officers were waiting for a court order. Bashkov said the reporter asked to find him a lawyer, but an hour later Borodin called back and said it was a false alarm.

Leonid Volkov, another acquaintance of Borodin who was head of Yekaterinburg headquarters for Russian opposition leader Alexei Navalny, cast doubt on the reports of a mysterious death. But he also suggested that the journalist most likely committed suicide out of desperation: Volkov said that Borodin wanted to move to Moscow, hoping to find an outlet that would give him more freedom to write.

“This story is not about how the regime kills one journalist who writes on inconvenient topics,” Volkov wrote on Facebook. “This is the story of how the regime kills thousands of journalists, all of them embodied [in Borodin], depriving them of any prospect, forcing them to choose between honor and a piece of bread every day.”

Borodin regularly covered high-profile corruption cases and crime in Russia. In February, he broke a story about Russian mercenaries who died in an armed confrontation with US forces near Deir-Ezzor, Syria. Borodin wrote about three members of Wagner, a private military company linked to pro-Putin oligarch Yevgeny Prigozhin.

Prigozhin, who is under US sanctions, is alleged to have made a systematic effort to silence reports of his activities.

Borodin was previously targeted for his views.

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.

Russia ranks first in the European Federation of Journalists list of countries with the highest number of journalists murdered in Europe. Since 1990, 346 journalists and media staff have been killed in Europe, and a third lost their lives in Russia.

In a statement on Twitter, Harlem Désir, the media freedom representative for the Organization for Security and Co-operation in Europe, an intergovernmental body, expressed “serious concern” about Borodin’s death.

“I call on the authorities for a swift and thorough investigation,” he said.