According to Radio Free Europe/Radio Liberty, Isayev was arrested under a Baku court ruling on December 14. The Azerbaijani government statement doesn't say on what grounds he was arrested and what charges he is facing.
"Elvin Isayev, a citizen of the Republic of Azerbaijan, born in 1980, was deported to Azerbaijan on December 12, 2019, for the violation of immigration laws in Ukraine," the migration service said in a report on December 15.
Kyiv has not yet commented on the situation.
Isayev had lived in Russia since 1998 where as a blogger he criticized the Azerbaijani president and called him a "dictator," while also writing about corruption in his home country.
Isayev was granted Russian citizenship three years later. However, a court in St. Petersburg on August 26 ruled to strip him of Russian citizenship and expel him. Isayev was subsequently placed in a temporary jail for foreign citizens.
His deportation to Azerbaijan in September was suspended based on an interim measure of the European Court of Human Rights called "Rule 39." He moved to Ukraine that same month.
Ukrainian media started reporting about Isayev's disappearance in Kyiv on December 12.