According to his daughter, Liudmyla Melnykova, Oleh Plachkov and his wife, Tatiana Plachkova, were abducted on 25 September 2023. "People with assault rifles in special-purpose uniforms burst into our home, put handcuffs on my parents, took their phones and documents, and drove them away. They locked my grandmother in a room and ordered her not to leave," recounted the Plachkovs' daughter Liudmyla Melnykova. The abductors did not conceal that they were from the FSB. They were particularly interested in Tatiana's Ukrainian phone number and the Telegram account on it. During the search, the Plachkovs were beaten.

The family did not receive any official notification of the detention. According to Liudmyla, her parents were held in basements in a factory, where partitions had been set up to hold people. According to testimonies of other captives, conditions in detention were cold, there was a lack of food, clothing, and medical care, and people were tortured. Officials from the Russian government agencies replied to Liudmyla Melnykova's inquiries, claiming that they had not detained Oleh Plachkov and did not know his whereabouts. Liudmyla suspects that he may have been moved between various places of detention in the occupied territory of Zaporizhzhia Oblast. According to the Crimean Tatar Resource Centre, Oleh Plachkov was held for some time in the Pre-Trial Detention Centre in Melitopol, after which he was transferred to Pre-Trial Detention Centre No. 8 in occupied Crimea.

It is not known whether charges have been brought against Oleh Plachkov. He may possibly have been charged with "espionage," like his wife Tatiana Plachkova, who died in detention, but there is no confirmation of this.

Before the Russian Federation's full-scale war against Ukraine, Tatiana and Oleh Plachkov owned two cafés in Melitopol and ran their own business. After the occupation of Melitopol, the couple decided to remain due to their responsibilities towards their elderly parents and the café employees.