Ukrainian citizens Oleh Sentsov and Oleksandr Kolchenko, who have been convicted in Russia, signed the documents necessary for their extradition in early April, 2016, however, the Russian Justice Ministry has not confirmed receiving them yet, Kolchenko's defense lawyer Svitlana Sydorenko told the Echo of Moscow radio station.

"All the documents were signed in early April and these documents were to be delivered to the Justice Ministry, and they probably did... They filled in these documents long ago, when there was a debate over the fact that the Russian Justice Ministry made a request to the Federal Penitentiary Service Russia, they signed these documents as early as at the beginning of April," Sydorenko said.

Meanwhile, the Russian Justice Ministry has not officially acknowledged the receipt of the documents, she said.

According to Sydorenko, similar extradition documents have been already signed by Ukrainians Hennadiy Afanasyev and Yuriy Soloshenko, who were convicted, in Russia, which were sent at the same time as the papers of Sentsov and Kolchenko.

On August 25, 2015, the North Caucasus District Military Court in Rostov-on-Don issued a guilty verdict against Sentsov to a cumulative term of 20 years in a high-security prison for the alleged "preparation of terror attacks in Crimea".

On December 25, 2015, the Moscow City Court convicted Afanasyev of a terrorist attack and sentenced him to seven years in a high-security prison. Kolchenko was sentenced to ten years in a high-security prison.

On October 15, 2015, the Moscow City Court sentenced Yuriy Soloshenko, 73, former director of the Ukrainian plant Zarya, to six years in a high-security penal colony for espionage for Ukraine.

On March 10, 2016, the Ukrainian Justice Ministry said it sent a request to the Russian counterparts asking them to hand over Ukrainians Oleh Sentsov, Hennadiy Afanasyev, Oleksandr Kolchenko, and Yuriy Soloshenko, convicted by Russian courts to Ukraine under the Convention on the Transfer of Sentenced Persons.