He is Viktor Medvedchuk, the pro-Russian opposition figure known as Vladimir Putin's top figure in Ukraine. He had been under house arrest for months in Kyiv, fleeing shortly after Russia invaded Ukraine.
Now, according to the Kyiv authorities, he was caught at the border by the Ukrainian secret service SBU while trying to escape the country. Ukrainian President special database Volodymyr Zelenskiy first announced the news on Facebook. In just a few hours, the post with the picture has received more than 170,000 likes. The message is quite "we got him". Given his close ties to the Kremlin, Medvechuk is an iconic figure on the Ukrainian contemporary political scene who has been demonized by some.