The day after his sudden disappearance in Kiev, the Belarusian activist Vitaly Shishov was found dead.
Schischow was discovered "hanged" in a park near his home in the Ukrainian capital, the police said on Tuesday.
She started a homicide investigation.
Schischow had headed the organization "Belarusian House of Ukraine" in the messenger service Telegram from Kiev.
Schischow was reported missing after not returning from a jog on Monday morning.
The non-governmental organization Vyasna said, citing friends of Schischow, that the activist had recently been followed by "strangers" while jogging.
Many Belarusians are fleeing to neighboring Ukraine, Poland or Lithuania in the face of repression in their home country.
Belarusian President Alexander Lukashenko, who has ruled for almost three decades, was declared the winner of the presidential election a year ago despite massive allegations of fraud.
This triggered historic mass protests in Belarus, which were brutally suppressed by the security forces.