After the occupation and annexation of the Autonomous Republic of Crimea, Russia launched an undeclared hybrid war against Ukraine. The aggressor embodied the plan of the "Russkaya vesna” and spread the threat to a number of peaceful regions of the state. Artificially inspired pro-Russian protests, accompanied by the seizure of state and local government in eastern Ukraine by armed militants, aimed to destabilize the socio-political situation and paralyze the military and law enforcement systems of Ukraine.

In April 2014, under the leadership of representatives of the Russian special services, terrorists seized the administrative buildings of the Security Service of Ukraine in Luhansk region. Some local law enforcement officers betrayed the Motherland and deliberately sided with illegal armed groups, helping them to further spread the wave of pro-Russian separatism in Donbas. However, there were those who, risking their lives, tried to resist the criminals.

Such was the operative lieutenant colonel Oleh Tkachenko, who devoted 13 years to serving in the SSU.

After the capture of Luhansk by pro-Russian terrorists, the officer actually went into hiding. While gathering intelligence and documenting terrorist crimes in the temporarily occupied territory of Ukraine, he was kidnapped by militants of illegal armed groups led by a group of Russian special services who found pro-Ukrainian activists and law enforcement officers in the occupied territories.

After brutal torture on July 29, 2014, Oleh Tkachenko, who remained faithful to the Oath, was killed.

Oleh Tkachenko is survived by his wife and son.