[2][3] In January 2021, Onishchenko, as a member of the Russian network of influence, was personally sanctioned in the United States in connection with his interference in the American elections and the distribution of edited audio recordings of conversations between former American and Ukrainian officials in order to spread false allegations of corruption in Ukraine.

[9] Onyshchenko has also been implicated in running a fraud and money laundering scheme that traded approximately US$1.5 billion in illicit assets.

While in exile, Onyshchenko reportedly bought a horse stud farm with intentions to host invitational equestrian tournaments.

Sergiyenko was arrested by the National Anti-Corruption Bureau of Ukraine (NABU) as part of an investigation into alleged embezzlement and money laundering.

During his arrest on September 27, 2016, he sustained injuries, including contusions to his chest, hands, and nose, due to the use of force by NABU officers.

On November 7, 2024, the ECHR ruled: The judgment emphasizes the need for independent investigations into alleged misconduct by law enforcement agencies and the importance of timely judicial reviews to protect the rights of individuals deprived of their liberty.

The case also highlighted systemic issues within the investigative processes of NABU and underscored the necessity of enhancing human rights standards in Ukraine.

[18] A court ruling stated it was "likely" that his extradition "would not meet minimum standards of international law on conditions of detention", including the European Convention on Human Rights.

[18] On 11 January 2021, Onyshchenko was put on the US Sanctioned Persons list due to attempt to influence U.S. Presidential elections.

[13] In 2013, Onyshchenko bought FC Arsenal Kyiv[22][23] which at the end of the same year was announced as bankrupt and was withdrawn from the football competitions (see 2013-14 Ukrainian Premier League).

[6] Onyshchenko was married to Miss Ukraine 1997 Kseniya Kuzmenko until mid 2009, living mostly in Belgium, and has a child Олександр Olexandr or Sasha (b.

[15] Onyshchenko was dating Ganna Rizatdinova, an Olympic award-winning Ukrainian rhythmic gymnast, who is 24 years younger than him.

[30] In August 2016, Onyshchenko moved to London, UK because he feared for his life claiming "president (Petro Poroshenko) organises everything to kill me.