(CNN) — Russian Deputy Minister of Science and Higher Education Pyotr Kucherenko, who was on the plane, died Saturday of unknown causes.

The Russian Ministry of Science and Higher Education said in a statement posted on its website that “Kuchirenko felt the pain while on a flight with a Russian delegation returning from a business trip to Cuba.”

“The plane landed in Mineralni Vodi town and doctors tried to help him but they did not succeed in saving him,” he added.

The ministry expressed its condolences to his family and friends.

Kucherenko’s family said his death “may have been caused by heart disease, but a medical examination of the body will be carried out on Wednesday,” state channel “Zvesta” reported.

Journalist Roman Soper said via Telegram that he spoke with Kucherenko “a few days ago” before he left Russia, saying Kucherenko feared for his safety.

Sober said Kucherenko encouraged him to leave Russia after Russia invaded Ukraine last year: “Save yourself and your family, leave quickly, you cannot imagine the level of brutality of our state.”

When Super asked him if he wanted to leave too, according to him, Kucherenko replied, “Can’t do it anymore, they took our passports.” She told him that she was taking anti-depressants and tranquilizers, and “It’s hard for me to sleep. , I feel bad, we’re all hostages, and no one can say anything, otherwise we’ll be immediately crushed like insects.”

Senior officials and executives die mysteriously in Russia Former Moscow Aviation Institute (MAI) dean Anatoly Gerashchenko died in an “accident” in September, the institute said in a statement.

Gerashchenko was the company’s president from 2007 to 2015.