MOSCOW — A Russian journalist who had reported recently on clandestine Russian paramilitary groups in Syria died on Sunday after falling from the balcony of his fifth-floor apartment in Yekaterinburg, the authorities there said.

The journalist, Maksim Borodin, 32, was hospitalized in a coma after he was found sprawled out below his balcony in the city’s Kirov district on Thursday, according to New Day, the local news agency where he had worked. On Sunday morning, he died.

Investigators summoned to the scene had found the door to his apartment locked from the inside, a police spokesman, Valery Gorelykh, told the local E1 news agency. “Those facts suggest that no one left the apartment and that there were probably no strangers there,” he said.

While the police are still investigating Mr. Borodin’s death, it is not being treated as suspicious, Russia’s Investigative Committee said in a statement.