On 15 June 1934, Bronisław Pieracki, the Polish minister of the interior, was assassinated by the Organization of Ukrainian Nationalists (OUN).

The chosen assassin, Hryhorii Matseiko (also known by his pseudonym "Gonta"), was a trusted member of the OUN.

[1] In the morning of 15 June 1934 Matseiko (aged 31) appeared at the Foksal Street in Warsaw in front of a social club frequented by Pieracki.

Sixteen OUN members, including Stepan Bandera and Mykola Lebed, were found guilty of organizing the assassination.

[citation needed] The actual assassin, Hryhorii Matseiko, never faced a judge; he died in Buenos Aires in 1966.