Ravil Maganov, the chief of Russia's second-largest oil firm Lukoil, died on Thursday after reportedly falling from a hospital window in Moscow. The 67-year-old had been working with Lukoil since the company's inception in 1993.
On Thursday, Lukoil said in a statement that Maganov had passed away following a "serious illness".
"Lukoil's many thousands of employees mourn deeply for this grievous loss and express their sincere condolences to Ravil Maganov's family," it said.
Reuters, citing several Russian media outlets, also reported that the 67-year-old, who was overseeing the firm's refining, production and exploration operations, plunged to his death.
There is also growing belief within the firm that Maganov killed himself, but the circumstances surrounding his fall were unclear as no evidence or documents supported the claims, sources close to Lukoil told Reuters.
However, people associated with Maganov told Reuters that him committing suicide was highly unlikely.
Maganov is the latest of a number of high-profile business executives to die in mysterious circumstances. In May, Russian media reported a former Lukoil manager, Alexander Subbotin, was found dead in the basement of a house outside Moscow. Several other senior executives with ties to Russia’s energy industry have also died in unclear circumstances in the past few months.
On March 3, Lukoil had expressed its concern over the "tragic events" in Ukraine and called for the "soonest possible end to armed conflicts" via negotiations.