A Belarusian anti-government activist was found dead in a park near his home in the Ukrainian capital, Kyiv, on Tuesday, and the police there said they had begun an investigation into whether it was a murder or a suicide.

The activist, Vitaly Shishov, went missing on Monday after going out for a morning jog, said his colleagues, who accused the Belarusian authorities of killing him.

On Tuesday, the Kyiv police said that he had been found hanged in the park and that their investigation included the possibility that the death was a “murder masked as a suicide.”

“The full picture of events will be confirmed after the questioning of witnesses, the analysis of video recordings” and other investigative steps, the police said.

Aleksandr G. Lukashenko, Belarus’s authoritarian leader since 1994, has long repressed dissent at home and jailed thousands after large-scale protests over his rule last year.

Now, events in recent weeks have signalled that he is also escalating his campaign against the growing number of Belarusian exiles abroad.

In May, Lukashenko forced the landing of a passenger plane with an exiled Belarusian activist aboard and had him arrested.

On Sunday, a Belarusian Olympic sprinter sought protection at a Tokyo airport as her nation tried to forcibly send her home from the summer Games. She said she feared for her safety after criticising her coaches and the country’s national Olympic committee.

Shishov was the director of the Belarusian House in Ukraine, an organsation that helped people trying to escape repression in Belarus after the anti-government protests last summer and autumn. He was 26, according to local news reports.

While the circumstances surrounding Shishov’s death remained murky, critics of Lukashenko quickly pointed the finger at his authoritarian regime.

“It is worrying that those who flee Belarus still can’t be safe,” Svetlana Tikhanovskaya, the pro-democracy Opposition leader from Belarus who fled the country last year.

Shishov disappeared after going out for a 9am jog near his Kyiv home on Monday, colleagues at Belarusian House said in a statement. Since fleeing to Ukraine last autumn, the statement said, he had organised aid for other exiles , staged anti-Lukashenko protests and petitioned the Ukrainian authorities to support the Belarusian diaspora.

Last week, according to his Facebook posts, Shishov helped put on a rally in Kyiv marking the 31st anniversary of Belarus’s independence from the Soviet Union.

His colleagues said that he believed he was being followed and that supporters in Belarus had warned him of potential threats to his life. He responded jokingly that if something happened to him, it might help his organisation get much-needed attention.

“Vitaly faced these warnings with stoicism and with humor,” the organisation said. “There is no doubt that this was a spy-organised operation to liquidate a Belarusian who was truly a danger to the regime.”

New York Times News Service